Add test for recording history embeddings search result metrics

Bug: 324135732
Change-Id: I183d660420b72761cb9868f9d20d2322f44ca5e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5615655


Reviewed-by: Orin Jaworski <orinj@chromium.org>
Commit-Queue: John Lee <johntlee@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1312962}