Clean up deprecated ZK metadata keys and methods

[Jackie-Jiang]

Clean up the deprecated keys and methods as planned after releasing 0.9.0.
Also remove the deprecated and unused BackfillSegmentUtils which accesses the deprecated keys.

Upgrade Notes

To keep backward-compatibility, the cluster need to run release 0.9.0 before upgrading so that both old and new version of ZK metadata can be read.

Release Note

The following fields are removed from the segment ZK metadata

• segment.name
• segment.table.name
• segment.type

The following fields are replaced with the new fields

• segment.offline.download.url, segment.realtime.download.url -> segment.download.url
• segment.offline.push.time -> segment.push.time
• segment.offline.refresh.time -> segment.refresh.time

[codecov-commenter]

Codecov Report

Merging #7846 (1e3e010) into master (fc3de45) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master    #7846      +/-   ##
============================================
- Coverage     71.69%   71.62%   -0.07%     
  Complexity     4089     4089              
============================================
  Files          1579     1579              
  Lines         80819    80781      -38     
  Branches      12017    12013       -4     
============================================
- Hits          57940    57862      -78     
- Misses        18971    19023      +52     
+ Partials       3908     3896      -12     

Flag	Coverage Δ
integration1	29.38% <83.33%> (-0.13%)	⬇️
integration2	27.84% <83.33%> (-0.03%)	⬇️
unittests1	68.69% <100.00%> (+0.02%)	⬆️
unittests2	14.61% <50.00%> (-0.03%)	⬇️

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

Impacted Files	Coverage Δ
.../core/realtime/PinotLLCRealtimeSegmentManager.java	78.97% <ø> (-0.08%)	⬇️
...lix/core/realtime/PinotRealtimeSegmentManager.java	83.76% <ø> (-1.21%)	⬇️
...ot/controller/helix/core/util/ZKMetadataUtils.java	100.00% <ø> (ø)
...manager/realtime/HLRealtimeSegmentDataManager.java	82.79% <ø> (-0.16%)	⬇️
...va/org/apache/pinot/spi/utils/CommonConstants.java	23.63% <ø> (-2.68%)	⬇️
...not/common/metadata/segment/SegmentZKMetadata.java	82.63% <100.00%> (+8.08%)	⬆️
...ntroller/helix/core/PinotHelixResourceManager.java	64.27% <100.00%> (-0.08%)	⬇️
...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%)	⬇️
... and 21 more

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