This reverts commit 281b12d2.

Reason for revert: Broke bots.

Original change's description:
> infra: Add different builder group from ci/try.
>
> Uses the 'client.angle' and 'tryserver.angle' naming scheme that
> both V8 and WebRTC use. Necessary for the scripts to work with
> swarming tests.
>
> Bug: angleproject:5114
> Change-Id: I107cf0018e2173117e1d90e840b8e1419e69ef55
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2854277
> Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
> Commit-Queue: Jamie Madill <jmadill@chromium.org>

Bug: angleproject:5114
Change-Id: I2501f3ad89bc21d80ccdeabd52234a1fc5b39a49
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2855594Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>