[core] Set EVA Rank fallback for mobs with no subjob.

[UmeboshiXI]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

Closes #8380

For mobs with no subjob, JobSkillRankToBaseEvaRank() couldn't find an appropriate skill rank for the subjob since subjob was "None/0". This caused an error to get thrown in map.

Steps to test these changes

1. Give yourself GM
2. !zone to a burning circle with a maat fight. All Maats should have subjob 0 so any should do for this test.
3. Enter a Maat BCNM.
4. After cutscene and Maat is spawned, check map.exe log
5. Do not see the following error in map: JobSkillRankToBaseEvaRank: rank not implemented. Job SKILL_EVASION rank is likely not valid or no longer exists (A- rank in particular.)