Add Dawn Linux UHD 630 experimental tester

Adds a Dawn tester for qualifying Linux/UHD 630 configurations and a
manual trybot mirror.

Bug: 41496254
Change-Id: I37814c747d941cb624b510dcef16640e5969f198
Validate-Test-Flakiness: skip
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5421239


Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Auto-Submit: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1282200}