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

[Sam Clegg via llvm-commits]

sbc100 wrote:

It looks like this broke the `asan.test_externref_emjs_dynlink` test in emscripten. 

I will disable that test for now and hopefully we can fix forward.

https://github.com/llvm/llvm-project/pull/83196