fix: port already in use & nccl errors in gpu tests

[deependujha]

What does this PR do?

Reverts #21309
closes #21313 #21311

thanks, pr: #21341

• This revert removes the port management logic and switches to a simpler approach for addressing port-related issues, as this is specific to standalone test environments.
• The initial step for this change has been introduced in Lightning-AI/utilities — reference: feat: specify standalone port utilities#447

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📚 Documentation preview 📚: https://pytorch-lightning--21335.org.readthedocs.build/en/21335/

[codecov]

Codecov Report

❌ Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 87%. Comparing base (19912d0) to head (4927768).

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #21335   +/-   ##
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- Coverage      87%      87%   -0%     
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  Files         270      269    -1     
  Lines       23799    23708   -91     
=======================================
- Hits        20629    20536   -93     
- Misses       3170     3172    +2