Fix #76943: Inconsistent stream_wrapper_restore() errors

Fix #76943: Inconsistent stream_wrapper_restore() errors

If restoring of any not registered built-in wrapper is requested, the
function is supposed to fail with a warning, so we have to check this
condition first.

Furthermore, to be able to detect whether a built-in wrapper has been
changed, it is not sufficient to check whether *any* userland wrapper
has been registered, but rather whether the specific wrapper has been
modified.

Closes GH-6183.