can't read metrics from nebula-graph which version is nightly

[kqzh]

The problem is caused by different nebula version has different stats format, nebula_stats_exporter don't compatibility nightly version now.

# curl nightly metad http://192.168.8.91:19559/stats?stats=

heartbeat_latency_us.avg.5=254
heartbeat_latency_us.avg.60=294
heartbeat_latency_us.avg.600=252
heartbeat_latency_us.avg.3600=231
heartbeat_latency_us.p75.5=627
heartbeat_latency_us.p75.60=647
heartbeat_latency_us.p75.600=626
heartbeat_latency_us.p75.3600=615
heartbeat_latency_us.p95.5=925
heartbeat_latency_us.p95.60=929
heartbeat_latency_us.p95.600=925
heartbeat_latency_us.p95.3600=923
heartbeat_latency_us.p99.5=985
heartbeat_latency_us.p99.60=985
heartbeat_latency_us.p99.600=985
heartbeat_latency_us.p99.3600=984
num_heartbeats.rate.5=0
num_heartbeats.rate.60=0
num_heartbeats.rate.600=0
num_heartbeats.rate.3600=0
num_heartbeats.sum.5=2
num_heartbeats.sum.60=12
num_heartbeats.sum.600=118
num_heartbeats.sum.3600=708
...

# curl v2.0.1 metad http://192.168.8.166:19559/stats?stats=

value=0
name=heartbeat_latency_us.avg.5
value=0
name=heartbeat_latency_us.avg.60
value=0
name=heartbeat_latency_us.avg.600
value=0
name=heartbeat_latency_us.avg.3600
value=0
name=heartbeat_latency_us.p75.5
value=0
name=heartbeat_latency_us.p75.60
value=0
name=heartbeat_latency_us.p75.600
value=0
name=heartbeat_latency_us.p75.3600
value=0
name=heartbeat_latency_us.p95.5
value=0
name=heartbeat_latency_us.p95.60
value=0
name=heartbeat_latency_us.p95.600
value=0
name=heartbeat_latency_us.p95.3600
value=0
name=heartbeat_latency_us.p99.5
value=0
name=heartbeat_latency_us.p99.60
...

# curl exporter http://192.168.8.111:9100/metrics

# HELP nebula_graphd_count 
# TYPE nebula_graphd_count gauge
nebula_graphd_count{componentType="graphd",instanceName="graphd0",namespace="nebula"} 1
# HELP nebula_metad_count 
# TYPE nebula_metad_count gauge
nebula_metad_count{componentType="metad",instanceName="metad0",namespace="nebula"} 1
# HELP nebula_storaged_count 
# TYPE nebula_storaged_count gauge
nebula_storaged_count{componentType="storaged",instanceName="storaged0",namespace="nebula"} 1
# HELP promhttp_metric_handler_errors_total Total number of internal errors encountered by the promhttp metric handler.
# TYPE promhttp_metric_handler_errors_total counter
promhttp_metric_handler_errors_total{cause="encoding"} 0
promhttp_metric_handler_errors_total{cause="gathering"} 0
# HELP promhttp_metric_handler_requests_in_flight Current number of scrapes being served.
# TYPE promhttp_metric_handler_requests_in_flight gauge
promhttp_metric_handler_requests_in_flight 1
# HELP promhttp_metric_handler_requests_total Total number of scrapes by HTTP status code.
# TYPE promhttp_metric_handler_requests_total counter
promhttp_metric_handler_requests_total{code="200"} 12
promhttp_metric_handler_requests_total{code="500"} 0
promhttp_metric_handler_requests_total{code="503"} 0