This reverts commit 8f26346b.

Reason for revert: Should be fixed by updated exclusion spec.

Original change's description:
> Temporarily remove standalone tester bots from CQ.
>
> Due to RECIPE CRASH, e.g.
> https://ci.chromium.org/ui/p/angle/builders/try/linux-clang-rel/21245/overview
>
> No-try: true
> Bug: angleproject:5114
> Change-Id: I42f76fb370ee5423430955643bffb8c2204fa25f
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2875717
> Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
> Commit-Queue: Yuly Novikov <ynovikov@chromium.org>

Bug: angleproject:5114
Change-Id: I781a5a409a9ede005feaf0f3d7bcedac31eaa036
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2876986Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>