Add BackupUtils#waitUntilBackupServiceIsRunning

This is required in CTS tests to know when backup service init is finished.

Bug: 131307343
Test: atest BackupUtilsTest
Change-Id: Ifdd729c433bcd26f0fdcf1b56c9106b00c75845f
3 files changed
tree: 9079b2a6924100103a0e5ebbbe1098510fa9192a
  1. build/
  2. common/
  3. tools/
  4. OWNERS
  5. PREUPLOAD.cfg
  6. test_defs.sh