Deprecate stopForeground(boolean)

It was superseded in API 24 (Android N), and does not actually behave
the way that developers assume.  Everyone should use the modern version
nowadays, and there's already a ServiceCompat facility provided in
Jetpack to handle legacy deployment issues.

Bug: 195653704
Test: m offline-sdk-docs (no implementation changes)
Test: verify platform build
Change-Id: Ia014998b91da732ef26cc796d23e57c727fd067a