Reason for revert:
The build config is now working again.
Original issue's description:
> CQ: Remove Linux ARM64 Debug trybot from default set.
>
> It appears recent changes in Chromium (crbug.com/708104) is causing
> this to fail.
> Need to disable this to unblock rolling.
>
> BUG=webrtc:7024
> TBR=oprypin@webrtc.org
>
> Review-Url: https://codereview.webrtc.org/2790263003 .
> Cr-Commit-Position: refs/heads/master@{#17521}
> Committed: 5115645c01
TBR=oprypin@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:7024
Review-Url: https://codereview.webrtc.org/2805603003
Cr-Commit-Position: refs/heads/master@{#17560}