Revert #75624 "Improve invlet management for Magiclysm spell list."

[Naadn]

Is your feature request related to a problem? Please describe.

This PR broke the whole spellcast menu that I can't even test spells in newest experiment build.

Solution you would like.

Revert #75624

Describe alternatives you have considered.

Let it remain broke until someday someone fix it.

Additional context

No response

[BaumgeistOne]

What exactly do you mean by "broke"? Is it the same as #76085?

[Naadn]

What exactly do you mean by "broke"? Is it the same as #76085?

More like #76042, I choose to cast A but it cast B instead, and when I choose B it cast F and so on.

[RenechCDDA]

This is not appropriate for a suggestion. Please put some further thought into your ideas before opening any further issues. In particular, calling for a revert is never a valid suggestion - at that point you're just trying to tell people what they should work on. That's not how we (or any FOSS) work.