Do not sort the instances in InstancePartitions

[Jackie-Jiang]

We should not sort the instances in the generated InstancePartitions because:

1. It will lead to different assignment result comparing to default consuming segment assignment, which makes migration hard
2. It will lead to skewed partition assignment within replica group when numInstancesPerReplicaGroup doesn't match stream partitions - the instances with smaller names tend to get more partitions across multiple tables

One thing to call out is that after this fix the mirror'ed servers for different replica can change, thus certain segment movement can be expected.

[codecov-commenter]

Codecov Report

Merging #9866 (d070c09) into master (aa839c9) will decrease coverage by 42.20%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             master    #9866       +/-   ##
=============================================
- Coverage     70.38%   28.17%   -42.21%     
+ Complexity     5013       53     -4960     
=============================================
  Files          1972     1960       -12     
  Lines        105687   105332      -355     
  Branches      15988    15950       -38     
=============================================
- Hits          74383    29673    -44710     
- Misses        26109    72724    +46615     
+ Partials       5195     2935     -2260     

Flag	Coverage Δ
integration1	25.14% <ø> (-0.01%)	⬇️
integration2	24.71% <ø> (-0.11%)	⬇️
unittests1	?
unittests2	?

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

Impacted Files	Coverage Δ
...nstance/InstanceReplicaGroupPartitionSelector.java	0.00% <ø> (-91.72%)	⬇️
...ain/java/org/apache/pinot/spi/utils/LoopUtils.java	0.00% <0.00%> (-100.00%)	⬇️
...in/java/org/apache/pinot/spi/utils/BytesUtils.java	0.00% <0.00%> (-100.00%)	⬇️
...java/org/apache/pinot/spi/trace/BaseRecording.java	0.00% <0.00%> (-100.00%)	⬇️
...java/org/apache/pinot/spi/trace/NoOpRecording.java	0.00% <0.00%> (-100.00%)	⬇️
...ava/org/apache/pinot/spi/config/table/FSTType.java	0.00% <0.00%> (-100.00%)	⬇️
...ava/org/apache/pinot/spi/config/user/RoleType.java	0.00% <0.00%> (-100.00%)	⬇️
...ava/org/apache/pinot/spi/data/MetricFieldSpec.java	0.00% <0.00%> (-100.00%)	⬇️
...ava/org/apache/pinot/spi/stream/StreamMessage.java	0.00% <0.00%> (-100.00%)	⬇️
...java/org/apache/pinot/common/tier/TierFactory.java	0.00% <0.00%> (-100.00%)	⬇️
... and 1345 more

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[jackjlli]

Do we have the context on why the sort was added at the first place? I'm good with removing the sort.

[Jackie-Jiang]

Do we have the context on why the sort was added at the first place? I'm good with removing the sort.

It is there in the first version when the feature is added. I think it is sorted probably because it is easier for human read. The minimize movement feature doesn't return sorted instances, so I believe we don't rely on the list to be sorted.