Fix setting device effects applier

Without this CL, setting a device effects applier causes the system to
crash. The applier is allowed to be set only once so if a system service
sets it via NotificationManagerInternal before NotificationManager
processes boot phases, a crash is observed at
PHASE_THIRD_PARTY_APPS_CAN_START because NM tries to set the default
device effects applier

Bug: 283030212
Test: atest ZenModeHelperTest
Flag: EXEMPT trivial
Change-Id: Ibbde8eca7748dcf31268853e957f7eac87956426