3.x: Update marbles of onErrorResume(Next|With) + cleanup

[akarnokd]

• onErrorResumeNext marble now indicates the error and function-callback nature:

• onErrorResumeWith marble now has the correct name (and retains the original onErrorResumeNext style):

• Address now deprecated API usage of Mockito.
• Few other style corrections.

Fixes #7050

[codecov]

Codecov Report

Merging #7051 into 3.x will increase coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##                3.x    #7051   +/-   ##
=========================================
  Coverage     99.51%   99.51%           
- Complexity     6668     6669    +1     
=========================================
  Files           742      742           
  Lines         47275    47275           
  Branches       6374     6374           
=========================================
+ Hits          47045    47048    +3     
  Misses          106      106           
+ Partials        124      121    -3     

Impacted Files	Coverage Δ	Complexity Δ
.../main/java/io/reactivex/rxjava3/core/Flowable.java	100.00% <ø> (ø)	595.00 <0.00> (ø)
...ain/java/io/reactivex/rxjava3/core/Observable.java	100.00% <ø> (ø)	565.00 <0.00> (ø)
...l/operators/observable/ObservableFlatMapMaybe.java	90.14% <0.00%> (-4.93%)	2.00% <0.00%> (ø%)
.../operators/flowable/FlowableBlockingSubscribe.java	93.02% <0.00%> (-4.66%)	10.00% <0.00%> (-1.00%)
...tivex/rxjava3/internal/jdk8/ParallelCollector.java	93.57% <0.00%> (-4.59%)	2.00% <0.00%> (ø%)
...a3/internal/subscribers/InnerQueuedSubscriber.java	97.72% <0.00%> (-2.28%)	16.00% <0.00%> (-1.00%)
...ernal/operators/flowable/FlowableFlatMapMaybe.java	93.78% <0.00%> (-1.56%)	2.00% <0.00%> (ø%)
...ava3/internal/operators/maybe/MaybeMergeArray.java	98.87% <0.00%> (-1.13%)	6.00% <0.00%> (ø%)
...ternal/operators/observable/ObservableGroupBy.java	98.90% <0.00%> (-1.10%)	2.00% <0.00%> (ø%)
...activex/rxjava3/processors/MulticastProcessor.java	99.54% <0.00%> (-0.46%)	82.00% <0.00%> (-1.00%)
... and 11 more

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