[infra] Remove Nexus5x jobs, move Wuffs to Pixel4

Bug: skia:12353
Change-Id: Ia4685f3f5e9e636d9b3b602140d23db6e375929c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/440459
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
3 files changed