fix MAT autosave re-render

[Stendarpaval]

• By moving the check for MAT's autosave setting into the hooked function, the combat tracker is only re-rendered outside of the autosaving process. This prevents the endless looping that can freeze the user's browser.
• Edit: To clarify, the problem was that previously the re-render function only gets added as a hook if MAT's autosaving setting is disabled while Foundry is loading. That means that it would work properly if the user would reload after enabling MAT's autosave setting. If they didn't, then the re-render function would still be hooked and start the endless loop.
• I tested this on both Foundry v0.8.9 and V9, using MAT v0.3.14. It seems to solve the problem discussed here.

[arcanistzed]

I've added these changes manually. Thanks!