Sanitize profile filename

[SkafteNicki]

What does this PR do?

Fixes #21365
Make sure that filenames are sanitized when profiler is trying to dump .prof files.
This will currently crash if there are characters such as "/" in the filename, which happens if the user has a ModelCheckpoint with a monitoring metric like "val/acc".

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📚 Documentation preview 📚: https://pytorch-lightning--21395.org.readthedocs.build/en/21395/

[codecov]

Codecov Report

❌ Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 79%. Comparing base (79ffe50) to head (ab7d8fb).
⚠️ Report is 6 commits behind head on master.
✅ All tests successful. No failed tests found.

❗ There is a different number of reports uploaded between BASE (79ffe50) and HEAD (ab7d8fb). Click for more details.

HEAD has 3345 uploads less than BASE

Flag	BASE (79ffe50)	HEAD (ab7d8fb)
cpu	777	30
lightning_fabric	195	0
pytest	390	0
python3.12	233	9
python3.12.7	232	9
lightning	388	15
python3.11	156	6
python3.10	78	3
python	78	3
pytorch2.1	78	6
pytest-full	387	30
pytorch_lightning	194	15
pytorch2.6	39	3
pytorch2.4.1	38	3
pytorch2.3	39	3
pytorch2.2.2	39	3
pytorch2.5.1	38	3
pytorch2.9	39	3
pytorch2.7	39	3
pytorch2.8	38	3

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #21395     +/-   ##
=========================================
- Coverage      87%      79%     -8%     
=========================================
  Files         269      266      -3     
  Lines       23804    23757     -47     
=========================================
- Hits        20626    18732   -1894     
- Misses       3178     5025   +1847     

[deependujha]

This looks like an internal flag, and it’s unclear how a user is meant to turn it off.

We should either sanitize unconditionally or treat this as a proper configuration option: pass it through the constructor and store it as an instance attribute so it can be used consistently later.