Replace using_pjrt() xla runtime device_type() check with in xla.py for torch-xla>=2.5

[byi8220]

What does this PR do?

Fixes #20419

torch_xla.runtime.using_pjrt() is removed in pytorch/xla#7787

If torch_xla version >= 2.5, this PR replaces references to that function with a check to device_type() to recreate the behavior of that function, minus the manual initialization

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📚 Documentation preview 📚: https://pytorch-lightning--20442.org.readthedocs.build/en/20442/

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 88%. Comparing base (8ce5287) to head (5ada0e1).
Report is 54 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #20442   +/-   ##
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- Coverage      88%      88%   -0%     
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  Files         267      267           
  Lines       23203    23207    +4     
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+ Hits        20313    20315    +2     
- Misses       2890     2892    +2     

[lantiga]

Looks good, thanks!