2 bots are added,
linux-swangle-try-tot-angle-x64 and win-swangle-try-tot-angle-x86

Also updated wrangling instructions to keep these CQ bots healthy,
and other SwANGLE bots at lower priority.

Bug: chromium:1007018
Change-Id: I38a1cc31eb4d787d192da087efce3cc619cb118d
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2131567Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>