[LLVM][Coroutines] Check variable decl scope instead of optimization level for...

[LLVM][Coroutines] Check variable decl scope instead of optimization level for hoisted DbgDeclare Loc (#92978)

Minor patch following up on
https://github.com/llvm/llvm-project/pull/75402.

The more generalized version of [this
error](https://github.com/llvm/llvm-project/pull/75104#issuecomment-1853497609)
is whenever we have a debug variable created in one subprogram scope
inlined into another subprogram scope. So instead of checking
optimization level, it is safer to just check whether the subprogram
scope of the variable matches the subprogram scope of the hoisted
position.