more MSAN dbg->rel cycling

Remove old Debug jobs that I added Release mirrors to
earlier today.  The release jobs look fine and faster,
taking between 50-80% the time of the debug jobs.

Add SwiftShader release MSAN jobs to try the same there.

Change-Id: I2a40e079bc95edc318d4da02299273fb0dd736af
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/270537
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
2 files changed