[OpenMP][NFC] Move the `noinline` to the parallel entry point

The `noinline` for non-SPMD parallel functions is probably not necessary
but as long as we use it we should put it on the outermost parallel
function, which is the wrapper, not the actual outlined function.

Resolves PR49752

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D99506