Fix the flaky TableCacheTest

[Jackie-Jiang]

The test is flaky because the table config and schema update is not atomic. It is okay for the update to be eventual consistency (update multiple maps in order). Enhance the test to handle that.

Example failure run: https://github.com/apache/pinot/runs/5132494061?check_suite_focus=true

[codecov-commenter]

Codecov Report

Merging #8185 (ba53375) into master (6844cb3) will increase coverage by 40.66%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             master    #8185       +/-   ##
=============================================
+ Coverage     30.67%   71.34%   +40.66%     
- Complexity        0     4303     +4303     
=============================================
  Files          1612     1623       +11     
  Lines         83962    84314      +352     
  Branches      12602    12640       +38     
=============================================
+ Hits          25754    60150    +34396     
+ Misses        55919    20036    -35883     
- Partials       2289     4128     +1839     

Flag	Coverage Δ
integration1	28.86% <ø> (-0.06%)	⬇️
integration2	27.55% <ø> (+<0.01%)	⬆️
unittests1	67.88% <ø> (?)
unittests2	14.18% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...data/manager/realtime/DefaultSegmentCommitter.java	0.00% <0.00%> (-80.00%)	⬇️
...er/api/resources/LLCSegmentCompletionHandlers.java	43.56% <0.00%> (-18.82%)	⬇️
...data/manager/realtime/SegmentCommitterFactory.java	88.23% <0.00%> (-11.77%)	⬇️
...altime/ServerSegmentCompletionProtocolHandler.java	51.42% <0.00%> (-6.67%)	⬇️
...core/startree/operator/StarTreeFilterOperator.java	85.31% <0.00%> (-2.10%)	⬇️
...lix/core/minion/PinotHelixTaskResourceManager.java	44.18% <0.00%> (-0.78%)	⬇️
...nMaxValueBasedSelectionOrderByCombineOperator.java	70.45% <0.00%> (-0.76%)	⬇️
...pache/pinot/core/query/utils/idset/EmptyIdSet.java	25.00% <0.00%> (ø)
...ata/manager/realtime/RealtimeTableDataManager.java	68.27% <0.00%> (ø)
...anager/realtime/SegmentBuildTimeLeaseExtender.java	63.23% <0.00%> (ø)
... and 1112 more

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