Add UnsupportedAppUsage to java_aconfig_library dependency

Generated flag requires UnsupportedAppUsage annotation to expose the
flag to CTS tests.

Bug: 301272559
Test: presubit
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:5e2c96a93b4c16b224c090570a10697400a42c0a)
Merged-In: I90c87596ca80766ece429ddee1b45723b01d2760
Change-Id: I90c87596ca80766ece429ddee1b45723b01d2760