2.x: Fix size+time bound window not creating windows properly

[akarnokd]

There was a logic error in the size+time bound window operator for when to close a window if timers are not restarted when the size-bound is hit.

Due to this bug, two tests were not receiving and thus accounting for empty windows that are happening when the size-bound is hit followed by the periodic time-bound hit.

Fixes #6651

[codecov]

Codecov Report

Merging #6657 into 2.x will increase coverage by <.01%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##                2.x    #6657      +/-   ##
============================================
+ Coverage     98.18%   98.19%   +<.01%     
- Complexity     6344     6347       +3     
============================================
  Files           677      677              
  Lines         45551    45551              
  Branches       6332     6332              
============================================
+ Hits          44725    44728       +3     
- Misses          259      266       +7     
+ Partials        567      557      -10

Impacted Files	Coverage Δ	Complexity Δ
...al/operators/observable/ObservableWindowTimed.java	90.73% <100%> (+0.27%)	4 <0> (ø)	⬇️
...ternal/operators/flowable/FlowableWindowTimed.java	91.17% <100%> (-0.23%)	4 <0> (ø)
...l/operators/observable/ObservableFlatMapMaybe.java	86.92% <0%> (-7.19%)	2% <0%> (ø)
...nternal/operators/observable/ObservableCreate.java	94.01% <0%> (-3.42%)	2% <0%> (ø)
...tivex/internal/schedulers/TrampolineScheduler.java	96.1% <0%> (-2.6%)	6% <0%> (ø)
...x/internal/operators/flowable/FlowablePublish.java	97.48% <0%> (-1.26%)	13% <0%> (ø)
...perators/mixed/ObservableConcatMapCompletable.java	98.49% <0%> (-0.76%)	3% <0%> (ø)
...x/internal/operators/flowable/FlowableGroupBy.java	95.51% <0%> (-0.57%)	3% <0%> (ø)
...ernal/operators/flowable/FlowableFromIterable.java	95.72% <0%> (-0.54%)	5% <0%> (ø)
...ternal/operators/observable/ObservableFlatMap.java	88.99% <0%> (-0.33%)	3% <0%> (ø)
... and 18 more

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