Fix perspective shift in construction

[akrieger]

Summary

None

Purpose of change

Fixes #78489. I broke logic which restored the UI after construction because I misunderstood the side effects of the code in question.

Describe the solution

The old code wrapped the restore_on_out_of_scope in a unique_ptr to allow manually triggering the restore. The broken code was instead cancelling the restore entirely. Put the unique_ptr logic back because that is correct. Keep restore_on_out_of_scope::cancel() because it might still be useful later.

Describe alternatives you've considered

Testing

It's putting the old logic back so it should Just Work (tm).

Reproduced the issue. Applied the fix. Entered and exited construction workflow and view did not stay shifted.

Additional context