Update neverallow rules for init_first_stage

We are introducing Microdroid-specific variant of the init_first_stage,
and need to add init_first_stage_defaults and
init_first_stage.microdroid to the neverallow rule.

Bug: 287206497
Test: build com.android.virt APEX
Change-Id: I88543256ab0479d4676865ebb1d16d9d39f1f455