Log net error and response code as strings.

When DMServer request fails, log strings representation of net errors
and/or DMServer response codes for better readability.

Bug: none
Test: none
Change-Id: I7c514e30de7954e3dfe0521531934a991497f60a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4896821
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Sergey Poromov <poromov@chromium.org>
Commit-Queue: Artem Sumaneev <asumaneev@google.com>
Auto-Submit: Artem Sumaneev <asumaneev@google.com>
Cr-Commit-Position: refs/heads/main@{#1202445}