Remove the uncertain field from the cache entry

We never store uncertain results in the cache so the field is redundant.

Change-Id: I886c786059211a8453b55e3d6719c6c46e38bd32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5826136
Reviewed-by: Tomek Jurkiewicz <tju@google.com>
Commit-Queue: Tomek Jurkiewicz <tju@google.com>
Auto-Submit: James Lee <ljjlee@google.com>
Cr-Commit-Position: refs/heads/main@{#1349112}