[WebAssembly] Use RefTypeMem2Local instead of Mem2Reg (#83196)

When reference-types feature is enabled, forcing mem2reg unconditionally
even in `-O0` has some problems described in #81575. This uses
RefTypeMem2Local pass added in #81965 instead. This also removes
`IsForced` parameter added in

https://github.com/llvm/llvm-project/commit/890146b19206827bc48ee1ae1dc1534ff2ff18d7
given that we don't need it anymore.

This may still hurt debug info related to reference type variables a
little during the backend transformation given that they are not stored
in memory anymore, but reference type variables are presumably rare and
it would be still a lot less damage than forcing mem2reg on the whole
program. Also this fixes the EH problem described in #81575.

Fixes #81575.