[Passwords] Switch CompromisedCredentials to patterned histograms

This CL is technically no-op, but a preparation for an upcoming CL that
will rename those metrics.

Here is the output of the verification command:
python3 ./tools/metrics/histograms/print_histogram_names.py
--diff origin/main

0 histograms added:
0 histograms removed:
0 histograms obsoleted:

Bug: 1259121
Change-Id: I625f345f5b954d54d996a58fa092a99ef185c93b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3344629
Reviewed-by: Viktor Semeniuk <vsemeniuk@google.com>
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Cr-Commit-Position: refs/heads/main@{#952444}