[coop-threading] Convert tests to wast

Tests written in Rust should be converted to wast

> I realize that this is preexisting (my comment here applies to other tests in this file too) and so you can defer this to later if you desire, but these tests are perfect for adding to `tests/misc_testsuite/**/*.wast` vs in-Rust tests here. Should be able to `(assert_trap (invoke ...) "the message")` and that makes the tests much easier to run and avoids compiling more Rust code for tests

_Originally posted by @alexcrichton in https://github.com/bytecodealliance/wasmtime/pull/11751#discussion_r2426838777_