Re-enable app_functions on Wear.

The Gemini team now has use-cases for using this service that they previously
did not have aligned on Wear at the time of b/361300136.

This leaves the infrastructure in place such that this can be still configured
across a few locations, which likely would be desirable on other form factors
such as TV and Auto for the time.

Bug: 372711850
Test: Build
Flag: EXEMPT - Feature is already flagged, this controls the Wear variant.
Change-Id: I4abf648a2abc2bcfb6737e6caf057357e7c0ddd4