Change Mac arm64 builder for CTS rolls

Changes the CTS roll config to use the new Mac arm64 CQ builder instead
of the manual-only trybot.

Bug: 1442214
Change-Id: I39f5598ee58670d5683dbc99c817315f17e2414f
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/164821
Reviewed-by: Austin Eng <enga@chromium.org>
Auto-Submit: Brian Sheedy <bsheedy@google.com>
Kokoro: Austin Eng <enga@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Brian Sheedy <bsheedy@google.com>
Commit-Queue: Austin Eng <enga@chromium.org>
diff --git a/tools/src/cmd/cts/config.json b/tools/src/cmd/cts/config.json
index 02d1efb..f99f128 100644
--- a/tools/src/cmd/cts/config.json
+++ b/tools/src/cmd/cts/config.json
@@ -57,7 +57,7 @@
     "Mac-Arm64": {
       "Project": "chromium",
       "Bucket": "try",
-      "Builder": "dawn-try-mac-arm64-rel"
+      "Builder": "mac-arm64-dawn-rel"
     },
     "Linux": {
       "Project": "chromium",