Weaken MFI Max Call Frame Size Assertion

A year ago when I was not invested at all into compilers, I found an assertion error when building an AArch64 debug build with LTO + CFI, among other combinations.

It was posted as a github issue here: https://github.com/llvm/llvm-project/issues/54088

I took it upon myself to revisit the issue now that I have spent some more time working on LLVM.

Reviewed By: MatzeB

Differential Revision: https://reviews.llvm.org/D151276