Grant additional permissions to uprobestats.

The `uprobestats` UID is granted `SET_ACTIVITY_WATCHER`,
`INTERACT_ACROSS_USERS_FULL`, and `REAL_GET_TASKS` permissions.

Bug: 440134516
Test: atest uprobestats-test
Flag: NONE just a permission change. Callsite will be flagged android.uprobestats.mainline.flags.use_process_observer_api
Change-Id: I0c40ee4b2f3b39e9f7bc7bde054aa6523be99286