Rename Mac bots to match reality.

Doing this separately from https://skia-review.googlesource.com/c/36040
to avoid confusion.

No-Try: true
Change-Id: I2d9e03c6da6096f9e14145d9654b9da7a8670036
Reviewed-on: https://skia-review.googlesource.com/35823
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
9 files changed