Remove vendor interface stability from internal power policy interface

- android.frameworks.automotive.powerpolicy.internal is not used by
vendor processes
- vendor interface stability is not needed

Bug: 214428116
Test: m android.frameworks.automotive.powerpolicy.internal-update-api &&
build okay

Change-Id: Id5b55a932cf33d6bed4209981965e8c6ed6fe78b
5 files changed