Mock init of PowerHalController in test

We have injected a MockedPowerHalController in PowerAdvisorTest, but it
will always run init once, which will try to connect a real PowerHAL.
This was resulting in a few error logs like SELinux denials.

Bug: 280438886
Test: libsurfaceflinger_unittest
Change-Id: Icbd0289cbeba95582eed01e61dcb748e2e167c24