[llvm] [WebAssemblyLowerEmscriptenEHSjLj] Avoid setting import_name where possible (PR #128564)

[Heejin Ahn via llvm-commits]

aheejin wrote:

Does the rationale in https://github.com/llvm/llvm-project/commit/296ccef70363df9195bc678ad5501dd44de7f8fb not apply anymore? I guess I can understand why it's unnecessary in case of C symbol + static linking but
- Is it fine in case of C symbols with dynamic linking?
- Is it fine in case of JS symbols with static/dynamic linking?

Now we have only two functions that are labeled with `wasm-import-module`: `invoke`s and `__cxa_matching_catch`s. Are they different from other JS functions?

https://github.com/llvm/llvm-project/pull/128564