[infra] Remove Debian11 RTX3060 jobs, fix dimension for Win RTX3060

We've lost all of our Debian11 RTX3060 machines due to bad disks, and it
looks like the Windows machines have updated so that the current `gpu`
dimension is out of date.

Change-Id: I0cb6263f211e42909e6f67f74e6a9ebfb2e1660b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/912501
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-by: Kaylee Lubick <kjlubick@google.com>
(cherry picked from commit 721bbd7c03401d40251d8618e86af42298ebee02)
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/918516