3.x: Remove unnecessary cancel/dispose calls from terminating using

[akarnokd]

Following up on a Gitter.im report, the onComplete/onError methods of the using operators were calling cancel/dispose on the upstream even though there is no reason to do such a thing and is also not allowed by Reactive Streams rule 2.3.

The original code's side-effect was that given a nested using pair, an onComplete/onError of the inner sequence would trigger a cancellation and resource release in the outer before/while the onComplete/onError signals propagate downstream and return back on a non-eager setting.

[codecov]

Codecov Report

Merging #7121 (0f4523e) into 3.x (3d5fece) will increase coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                3.x    #7121      +/-   ##
============================================
+ Coverage     99.49%   99.53%   +0.04%     
+ Complexity     6670     6669       -1     
============================================
  Files           742      742              
  Lines         47275    47267       -8     
  Branches       6374     6374              
============================================
+ Hits          47037    47048      +11     
+ Misses          112      100      -12     
+ Partials        126      119       -7     

Impacted Files	Coverage Δ	Complexity Δ
...va3/internal/operators/flowable/FlowableUsing.java	100.00% <ø> (ø)	2.00 <0.00> (ø)
...internal/operators/observable/ObservableUsing.java	100.00% <ø> (ø)	2.00 <0.00> (ø)
...l/operators/observable/ObservableFlatMapMaybe.java	92.25% <0.00%> (-4.93%)	2.00% <0.00%> (ø%)
...vex/rxjava3/internal/operators/maybe/MaybeAmb.java	96.96% <0.00%> (-3.04%)	10.00% <0.00%> (-1.00%)
...l/operators/observable/ObservableTimeoutTimed.java	99.15% <0.00%> (-0.85%)	3.00% <0.00%> (ø%)
.../operators/observable/ObservableCombineLatest.java	99.38% <0.00%> (-0.62%)	6.00% <0.00%> (ø%)
...a/io/reactivex/rxjava3/subjects/ReplaySubject.java	98.75% <0.00%> (-0.42%)	49.00% <0.00%> (ø%)
...ternal/operators/observable/ObservableFlatMap.java	97.87% <0.00%> (-0.36%)	3.00% <0.00%> (ø%)
...java3/internal/operators/flowable/FlowableZip.java	100.00% <0.00%> (+1.02%)	6.00% <0.00%> (ø%)
...ernal/operators/flowable/FlowableFromIterable.java	100.00% <0.00%> (+1.04%)	5.00% <0.00%> (ø%)
... and 6 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3d5fece...0f4523e. Read the comment docs.