refactor: standardize SIGTERMException instantiation to use explicit parentheses

[deependujha]

What does this PR do?

Fixes #<issue_number>

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---

📚 Documentation preview 📚: https://pytorch-lightning--21665.org.readthedocs.build/en/21665/

[azure-pipelines]

Azure Pipelines:
3 pipeline(s) require an authorized user to comment /azp run to run.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79%. Comparing base (0e20e15) to head (8b24b0b).
✅ All tests successful. No failed tests found.

❗ There is a different number of reports uploaded between BASE (0e20e15) and HEAD (8b24b0b). Click for more details.

HEAD has 546 uploads less than BASE

Flag	BASE (0e20e15)	HEAD (8b24b0b)
cpu	168	42
python	12	3
lightning_fabric	54	0
pytest	84	0
python3.12.7	36	9
python3.12	48	12
lightning	60	15
python3.11	24	6
python3.10	12	3
python3.13	36	9
pytorch2.1	12	6
pytest-full	84	42
pytorch_lightning	54	27
pytorch2.7	6	3
pytorch2.5.1	6	3
pytorch2.9	12	6
pytorch2.8	12	6
pytorch2.10	12	6
pytorch2.4.1	6	3
pytorch2.3	6	3
pytorch2.6	6	3
pytorch2.2.2	6	3

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #21665     +/-   ##
=========================================
- Coverage      87%      79%     -8%     
=========================================
  Files         270      267      -3     
  Lines       23973    23914     -59     
=========================================
- Hits        20748    18804   -1944     
- Misses       3225     5110   +1885