Rely on PlatformCompat instead of DeviceConfig

This change turns off the kill switch for App Enumeration by default
and sets the PlatformCompat feature to @Disabled until we're ready to
turn it on by default for beta.

Bug: 136675067
Test: atest AppsFilterTest
Test: atest AppEnumerationTests
Change-Id: I7f3c1995318838cda5d7025de8ae366cde75930f