[WebAssembly] Remove the `wasm-disable-fix-irreducible-control-flow-pass` switch (#185072)
This removes the `wasm-disable-fix-irreducible-control-flow-pass`
switch.
It was originally added in #67715 as a way to avoid the potentially
absurd compile times the pass used to bring. However with the successful
merge of #184441, the pass itself has been fixed to avoid this issue.
Given that, it is no longer necessary nor desirable to keep this switch.