Always update the permissions being delegated as Shell.

Previously the logic was to reuse the same permission delegate,
however since we are moving to the new API, that reuse is no longer
possible. So just always set up the permission delegate again to avoid
delegated permissions not being updated in PermissionManagerService.

Bug: 158736025
Fixes: 175085645
Test: MultiUserRollbackTest
Change-Id: I58acefe7bd9053a032b3df24c0c793f4e2aacde1