Protected Audience: add more seller worklet UMA

Add UMA metrics to understand how long a scoreAd() task waits
for its inputs and waits on queue to be run.

Change-Id: I0a4173ed51ee37e143aaa0673fd0648a85641b20
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5398020


Commit-Queue: Abigail Katcoff <abigailkatcoff@chromium.org>
Reviewed-by: Russ Hamilton <behamilton@google.com>
Reviewed-by: Orr Bernstein <orrb@google.com>
Cr-Commit-Position: refs/heads/main@{#1279883}