Will need to make CTF stop filing bugs with label:test_name anyway, because even if it is made read-only, we still need to query the bugs previously filed by CTF.

CTF doesn't set the test name in the label

https://cs.chromium.org/chromium/infra/appengine/chromium_try_flakes/handlers/flake_issues.py?l=378

An example bug filed by CTF: https://bugs.chromium.org/p/chromium/issues/detail?id=874944

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/90a6ab44d293f82bf61c782cf1475e49cad53769

commit 90a6ab44d293f82bf61c782cf1475e49cad53769
Author: Yuke Liao <liaoyuke@chromium.org>
Date: Thu Aug 16 20:32:14 2018

[FindIt] Remove unncessary code to check for label:test_name

Chromium-try-flakes doesn't file bug using label:test_name:
https://chromium.googlesource.com/infra/infra/+/7e5e0ead2f767773a59f9b621169dbd35b4df69a/appengine/chromium_try_flakes/handlers/flake_issues.py#378

So, FindIt doesn't need to search existing bugs using that query.

Bug:  808199 
Change-Id: I6f697f44777b6f6a9d54428519c88739e70a17f7
Reviewed-on: https://chromium-review.googlesource.com/1178636
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Shuotao Gao <stgao@chromium.org>
Reviewed-by: Jeffrey Li <lijeffrey@chromium.org>

[modify] https://crrev.com/90a6ab44d293f82bf61c782cf1475e49cad53769/appengine/findit/pipelines/flake_failure/test/create_bug_for_flake_pipeline_test.py
[modify] https://crrev.com/90a6ab44d293f82bf61c782cf1475e49cad53769/appengine/findit/pipelines/flake_failure/create_bug_for_flake_pipeline.py
[modify] https://crrev.com/90a6ab44d293f82bf61c782cf1475e49cad53769/appengine/findit/services/test/issue_tracking_service_test.py
[modify] https://crrev.com/90a6ab44d293f82bf61c782cf1475e49cad53769/appengine/findit/services/issue_tracking_service.py