2.x: update some marbles of Observable

[akarnokd]

Update/fix to a couple of marble diagrams in Observable:

• singleOrError: reuse existing
• combineLatestDelayError: reuse existing
• concatArrayEager: new diagram
• error: new diagrams
• fromFuture: new diagrams
• fromIterable: new diagram

[codecov]

Codecov Report

Merging #5351 into 2.x will increase coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                2.x    #5351      +/-   ##
============================================
+ Coverage     96.14%   96.18%   +0.04%     
+ Complexity     5781     5778       -3     
============================================
  Files           630      630              
  Lines         41162    41162              
  Branches       5721     5721              
============================================
+ Hits          39576    39593      +17     
+ Misses          621      612       -9     
+ Partials        965      957       -8

Impacted Files	Coverage Δ	Complexity Δ
src/main/java/io/reactivex/Observable.java	100% <ø> (ø)	506 <0> (ø)	⬇️
...al/operators/observable/ObservableSampleTimed.java	91.66% <0%> (-6.67%)	3% <0%> (ø)
...in/java/io/reactivex/subjects/BehaviorSubject.java	85.93% <0%> (-5.73%)	57% <0%> (+1%)
...rnal/subscriptions/DeferredScalarSubscription.java	93.84% <0%> (-4.62%)	27% <0%> (-1%)
...a/io/reactivex/internal/util/QueueDrainHelper.java	58.86% <0%> (-4.26%)	31% <0%> (-3%)
...reactivex/internal/operators/single/SingleAmb.java	96.36% <0%> (-3.64%)	9% <0%> (-1%)
...vex/internal/operators/flowable/FlowableTimer.java	92.85% <0%> (-3.58%)	2% <0%> (ø)
...internal/operators/completable/CompletableAmb.java	94.91% <0%> (-3.39%)	10% <0%> (-1%)
...x/internal/operators/maybe/MaybeSwitchIfEmpty.java	97.22% <0%> (-2.78%)	2% <0%> (ø)
...java/io/reactivex/subjects/CompletableSubject.java	94.8% <0%> (-2.6%)	35% <0%> (-1%)
... and 39 more

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