Fix FlakyTest annotation in TEST_MAPPING of mockingservicestests

This is a follow up of I059ca4cba35202862137285352e03008d8321da8.

Test: Pass all presubmit tests in mockingservicestests pass.
  $ atest --test-mapping frameworks/base/services/core/java/com/android/server
Bug: None
Change-Id: I0f780d3426fbe5a6e9e6ef4f5818852e5963a643