[Permissions] Add UMA for prediction service timeout

This change introduces telemetry to track when the permission prediction
service times out. A boolean is added to the FinishRequest method to
indicate if it was called as part of a timeout handling. We don't record
this metric when a request is cancelled.

This is recorded in the `Permissions.PredictionService.Timeout`
histogram via `PermissionUmaUtil`.

Bug: 441889637
Change-Id: I0c563bebdba6e89c791399e33d9a11cacffeb9cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6898594
Reviewed-by: Elias Klim <elklm@chromium.org>
Commit-Queue: Judith Hemp <hempjudith@google.com>
Cr-Commit-Position: refs/heads/main@{#1509579}