Don't clear profile on otapreopt.

`maybe_open_reference_profile` installs a hook that clears the profile
on destruction. This behavior is not expected. Fortunately, the cleanup
is blocked by a permission check, so it doesn't cause any damage.
However, it should not be attempted in the first place.

Bug: 300941544
Test: Run system/update_engine/scripts/update_device.py and see no more
  "Permission denied" error.

Change-Id: I4d98d33a305de2487669ae3d7d69bbc4b9f2615b