fix unpredictable panoptic_quality output when return_per_class=True

[i-aki-y]

What does this PR do?

Fix #2547

PanopticQuality can return per class score when return_per_class=True argument is given.
But the order of the result is unpredictable.

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

PR review

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If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

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📚 Documentation preview 📚: https://torchmetrics--2548.org.readthedocs.build/en/2548/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36%. Comparing base (8d9d2ae) to head (e4fc7b8).

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #2548     +/-   ##
========================================
- Coverage      69%     36%    -33%     
========================================
  Files         314     314             
  Lines       17663   17663             
========================================
- Hits        12179    6334   -5845     
- Misses       5484   11329   +5845     

[Borda]

Pls add entry to the changelog

[i-aki-y]

Added changelog entry.
Updated test codes to add missing test cases.