check duplicate exclusion cases in ProblemList files

[sophia-guo]

If there are more exclusion entries for same testcase only the last occurrence takes effects even if each entry has different tracked issue or different os-arch.

Testcase excluded by multiple lines happened quite a few times which causes confusion and wastes efforts to triage.

We should check ProblemList files for this to ensure no multiple entries is added, especially when PR is adding the new entry.

The main script for problemlist check is https://github.com/adoptium/aqa-tests/blob/master/scripts/disabled_tests/exclude_parser.py

#5863 (comment)

[sophia-guo]

See duplicate item
sun/security/ssl/X509TrustManagerImpl/distrust/Symantec.java https://github.com/adoptium/aqa-tests/issues/5955 generic-all

sun/security/ssl/X509TrustManagerImpl/distrust/Symantec.java https://github.com/adoptium/aqa-tests/issues/2123 generic-all

Duplicate item may refer to different issues with confusion and may be excluded on different os-arch with the first item being mistakenly ignored.

[adamfarley]

I agree this problem is a problem, and I'm happy to help resolve it.

We should also prevent duplicates between the exclude files and:

• The matching "unreliables" files (once merged).
• The matching "alpine" files