Update time zone spec for more timezone support

[Jackie-Jiang]

• Update zone-index.properties to include the new added timezone support from Presto
• Remove some unused fields

[Copilot]

Pull request overview

This PR updates timezone support in Apache Pinot by synchronizing with Presto's timezone definitions. The changes add new timezone entries, update comments for deprecated timezones, and remove unused fields and helper methods from the codebase.

Changes:

• Added 26 new timezone entries (e.g., Africa/Juba, Asia/Hebron, America/Ciudad_Juarez)
• Updated comment for deprecated US/Pacific-New timezone with removal reference
• Removed unused static fields and helper methods related to offset timezone calculations

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
zone-index.properties	Adds new timezone entries and updates deprecated timezone comment
TimeZoneKey.java	Removes unused offset timezone arrays and helper methods, refactors code formatting
DateTimeUtils.java	Removes unused FIXED_ZONE_OFFSET array and VARIABLE_ZONE constant

[codecov-commenter]

Codecov Report

❌ Patch coverage is 10.00000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.21%. Comparing base (92b6182) to head (beec045).

Files with missing lines	Patch %	Lines
.../org/apache/pinot/common/function/TimeZoneKey.java	10.00%	9 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #17543      +/-   ##
============================================
+ Coverage     63.20%   63.21%   +0.01%     
- Complexity     1476     1477       +1     
============================================
  Files          3170     3170              
  Lines        189523   189513      -10     
  Branches      28997    28999       +2     
============================================
+ Hits         119779   119802      +23     
+ Misses        60451    60414      -37     
- Partials       9293     9297       +4     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (ø)
integration	100.00% <ø> (ø)
integration1	100.00% <ø> (ø)
integration2	0.00% <ø> (ø)
java-11	63.17% <10.00%> (+0.01%)	⬆️
java-21	63.16% <10.00%> (-0.02%)	⬇️
temurin	63.21% <10.00%> (+0.01%)	⬆️
unittests	63.21% <10.00%> (+0.01%)	⬆️
unittests1	55.56% <10.00%> (+0.01%)	⬆️
unittests2	34.03% <0.00%> (+<0.01%)	⬆️

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[satwik-pachigolla]

This is purely adding more timezone identifier support. Looks good to me!