Update privapp-permissions for shell and systemui

The privileged flag is being added to the
SUBSCRIBE_TO_KEYGUARD_LOCKED_STATE permission. This commit updates
the privapp-permissions allowlists for the shell and systemui
packages to include this permission.

Bug: 380120712
Flag: android.security.subscribe_to_keyguard_locked_state_perm_priv_flag
Test: Manually verified device booted with permission flag update
Change-Id: Ibceb1a0bf81c573eef129fe82e50ab6cad2c3157