Refactor some AppSearch cts tests. Move testPutDocuments_emptyBytesAndDocuments to Base class. Bug: 275629842 Test: atest CtsAppSearchTestCases CtsAppSearchHostTestCases AppSearchServicesTests AppSearchCoreTests ContactsIndexerTests Change-Id: Ice9b74a9c42f3257f89867f1c35873b1502027a3