revert: fix($parse): handle promises returned from parsed function calls

This reverts commit 3a65822023119b71deab5e298c7ef2de204caa13.

The change cased regressions in third party components that require
promises from getter functions not to be unwrapped.

Since we have deprecated the promise unwrapping support in $parse it
doesn't make much sense to fix this issue and deal with regressions in
third party code.

Closes #4158