rm release swiftshader msan bots

They're not any faster than the debug ones.

Change-Id: I793706d36bd868277db2b6e39a53cb4e1075e0b1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/271880
Auto-Submit: Mike Klein <mtklein@google.com>
Commit-Queue: Ben Wagner aka dogben <benjaminwagner@google.com>
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
2 files changed