2.x: Fix O.blockingIterable(int) & add O.blockingLatest marbles

[akarnokd]

This PR fixes the Observable.blockingIterable(int) marble by using the blockingIterable redone earlier.

In addition, the PR adds a marble diagram to Observable.blockingLatest:

[codecov]

Codecov Report

Merging #5826 into 2.x will increase coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                2.x    #5826      +/-   ##
============================================
+ Coverage     96.41%   96.43%   +0.01%     
- Complexity     5813     5816       +3     
============================================
  Files           634      634              
  Lines         41761    41761              
  Branches       5796     5796              
============================================
+ Hits          40265    40272       +7     
- Misses          570      574       +4     
+ Partials        926      915      -11

Impacted Files	Coverage Δ	Complexity Δ
src/main/java/io/reactivex/Observable.java	100% <ø> (ø)	509 <0> (ø)	⬇️
.../operators/flowable/FlowableBlockingSubscribe.java	91.89% <0%> (-5.41%)	9% <0%> (-1%)
...ava/io/reactivex/processors/BehaviorProcessor.java	91.03% <0%> (-4.04%)	60% <0%> (+1%)
...ernal/operators/flowable/FlowableFlatMapMaybe.java	91.3% <0%> (-2.9%)	2% <0%> (ø)
...rnal/operators/flowable/FlowableTakeLastTimed.java	96.29% <0%> (-2.78%)	2% <0%> (ø)
...vex/internal/operators/single/SingleTakeUntil.java	93.44% <0%> (-1.64%)	2% <0%> (ø)
...a/io/reactivex/internal/util/QueueDrainHelper.java	60.41% <0%> (-1.39%)	34% <0%> (-1%)
...tors/observable/ObservableSequenceEqualSingle.java	98.29% <0%> (-0.86%)	3% <0%> (ø)
.../operators/observable/ObservableSequenceEqual.java	98.31% <0%> (-0.85%)	2% <0%> (ø)
...ernal/operators/flowable/FlowableTimeoutTimed.java	98.37% <0%> (-0.82%)	3% <0%> (ø)
... and 22 more

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