Shared Storage: Add boolean metric for SQL errors

Previously we have been using the
"Storage.SharedStorage.OnShutdown.NumSqlErrors" metric for
monitoring the API. But it is overly sensitive to a single user's
data. Here we add in a boolean version of the metric, which we will
switch to using for monitoring purposes.

Bug: 410800363
Change-Id: I4695e7a2b169ad528afe22d8dab1e9354b9a7497
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6458498
Reviewed-by: Yao Xiao <yaoxia@chromium.org>
Reviewed-by: Ayu Ishii <ayui@chromium.org>
Commit-Queue: Cammie Smith Barnes <cammie@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1447244}