[core] Fix scaling of range critical hit rate from AGI

[TracentEden2]

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• [x] 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?

This fixes a small issue related to critical hit rate calculation from AGI. Essentially, instead of using abs(dAGI), we should be using max(0, dAGI) so that negative dAGI do not have any impact on crit hit rate (this completes the fix started in my previous PR, and thus should have been there, my apologies). Also no source that I could find denotes a known cap (unlike for dDex and critical hit rate), thus I removed the cap (see bg-wiki here).

Steps to test these changes

Fight mobs with higher AGI and lower AGI (than player) and use RAs and track critical hit rate