Optimize and clean up ScanControllerTest

- Add more coverage. 10 more unit tests
- Reorganize tests to follow the order of ScanController
- Consolidate onBatchScanReportsInternal to a single test with @TestParameter
- Remove unused TestLooper

Bug: 404652736
Test: atest ScanControllerTest
Flag: EXEMPT test only
Change-Id: I5d104312c507eb7a74e0ab46f2eca24d3deae75c