Adds definitions for Debugd performance histograms

Adds histogram name and summary for several performance related
histograms for the Debugd utility. See https://crrev.com/c/3285832 for
the histogram-emitting code.

Bug: b:191179515
Change-Id: I85dc63355bb49e36291b67a1a8fb155113b648f8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3371397


Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Commit-Queue: Shervin Oloumi <enlightened@chromium.org>
Cr-Commit-Position: refs/heads/main@{#956781}