Upgraded Prometheus to further optimize ingester Push() on limits exceeded

[pracucci]

What this PR does:
I've got an optimization merged in Prometheus prometheus/prometheus#8620, so in this PR I'm upgrading it to pick up the benefits:

name                                                                                             old time/op    new time/op    delta
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_no_concurrency-12                  284µs ± 1%     296µs ±10%     ~     (p=0.222 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_low_concurrency-12                6.08ms ± 6%    6.34ms ± 9%     ~     (p=0.548 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_high_concurrency-12               70.1ms ±21%    71.4ms ± 4%     ~     (p=0.310 n=5+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_high_concurrency-12       188ms ±12%     149ms ±11%  -20.76%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_no_concurrency-12         647µs ±12%     458µs ± 1%  -29.22%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_low_concurrency-12       17.1ms ± 4%    11.4ms ± 7%  -33.40%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_no_concurrency-12       715µs ± 1%     559µs ± 2%  -21.80%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_low_concurrency-12     30.8ms ± 7%    27.8ms ±12%     ~     (p=0.056 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_high_concurrency-12     331ms ± 8%     316ms ± 4%     ~     (p=0.222 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_no_concurrency-12                  308µs ± 1%     294µs ± 1%   -4.51%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_low_concurrency-12                8.38ms ±12%    7.99ms ±10%     ~     (p=0.421 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_high_concurrency-12               83.8ms ± 5%    85.4ms ±11%     ~     (p=0.690 n=5+5)

name                                                                                             old alloc/op   new alloc/op   delta
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_no_concurrency-12                 2.11kB ± 1%    2.23kB ± 1%   +5.71%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_low_concurrency-12                 339kB ±30%     369kB ±37%     ~     (p=0.690 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_high_concurrency-12               26.2MB ±81%    34.5MB ±46%     ~     (p=0.421 n=5+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_high_concurrency-12       455MB ±10%     140MB ±30%  -69.24%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_no_concurrency-12         406kB ± 0%     100kB ± 0%  -75.50%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_low_concurrency-12       41.7MB ± 0%    10.5MB ± 1%  -74.81%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_no_concurrency-12       407kB ± 0%     100kB ± 0%  -75.29%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_low_concurrency-12     41.8MB ± 2%    10.1MB ± 1%  -75.76%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_high_concurrency-12     420MB ± 2%     117MB ± 0%  -72.23%  (p=0.016 n=5+4)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_no_concurrency-12                 99.0kB ± 0%    99.2kB ± 0%   +0.26%  (p=0.016 n=4+5)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_low_concurrency-12                10.4MB ± 1%    10.4MB ± 1%     ~     (p=0.690 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_high_concurrency-12                117MB ±22%     145MB ±27%     ~     (p=0.222 n=5+5)

name                                                                                             old allocs/op  new allocs/op  delta
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_no_concurrency-12                   40.0 ± 0%      41.0 ± 0%   +2.50%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_low_concurrency-12                 4.37k ± 8%     4.50k ±11%     ~     (p=0.690 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_order_samples,_scenario:_high_concurrency-12                 118k ±60%      144k ±37%     ~     (p=0.421 n=5+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_high_concurrency-12       5.23M ± 0%     2.15M ± 7%  -58.94%  (p=0.016 n=4+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_no_concurrency-12         5.04k ± 0%     2.03k ± 0%     ~     (p=0.079 n=4+5)
_Ingester_v2PushOnError/failure:_per-user_series_limit_reached,_scenario:_low_concurrency-12         507k ± 0%      205k ± 0%  -59.55%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_no_concurrency-12       5.04k ± 0%     2.04k ± 0%  -59.51%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_low_concurrency-12       509k ± 1%      204k ± 0%  -59.82%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_per-metric_series_limit_reached,_scenario:_high_concurrency-12     5.06M ± 1%     2.04M ± 0%  -59.62%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_no_concurrency-12                  2.04k ± 0%     2.04k ± 0%   +0.05%  (p=0.008 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_low_concurrency-12                  206k ± 0%      206k ± 0%     ~     (p=0.690 n=5+5)
_Ingester_v2PushOnError/failure:_out_of_bound_samples,_scenario:_high_concurrency-12                2.10M ± 4%     2.19M ± 6%     ~     (p=0.222 n=5+5)

Which issue(s) this PR fixes:
N/A

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[bboreham]

lgtm

[gouthamve]

LGTM