Drive-by clean-up: remove redundant operation

markProfileOwnerOnOrganizationOwnedDeviceUncheckedLocked sets
DISALLOW_REMOVE_MANAGED_PROFILE restriction on parent profil,
so doing it again in restrictRemovalOfManagedProfile is
unnecessary.

Bug: 162815601
Test: enroll TestDPC into COPE from SuW, check the profile cannot be
      removed.
Change-Id: Ie50c0cfa8affad58759ad3dd01963bb7edccf720