[AI Triage] Condense Search Calls

Right now, both the `OpenAiAnswerService` and `OpenAiLabeler` call azure search retrieving identical items. Can condense this into one call that way we don't call on search so much.

Start by locating OpenAiAnswerService and OpenAiLabeler and tracing where each retrieves items from Azure Search. Compare the two search calls and determine how their identical results can be shared without changing either service's behavior. Done means both services use one search operation and the relevant existing tests still pass.

Written by the indexing model from the issue text.