[clang] [CodeGen] Revert "Generate assume loads only with -fstrict-vtable-pointers" (PR #91900)

[Arthur Eubanks via cfe-commits]

aeubanks wrote:

adding assumes in general has issues: https://discourse.llvm.org/t/llvm-assume-blocks-optimization/71609

do you have proof that this change helps binaries and doesn't regress things? I have a feeling this will regress many things. `-fstrict-vtable-pointers` is still somewhat experimental

https://github.com/llvm/llvm-project/pull/91900