[perf] Don't use service-account-chromium-perf-dashboard.

It's a duplicate. Use service-account-chromeperf instead.

Bug: 839022
Change-Id: I59cbc9a1306f356375da1d2533bbd5c82a4647f2
Reviewed-on: https://chromium-review.googlesource.com/1043002Reviewed-by: Nodir Turakulov <nodir@chromium.org>
Commit-Queue: David Tu <dtu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556716}

infra/config/global/cr-buildbucket.cfg

@@ -1570,7 +1570,7 @@ buckets {
   }
   acls {
     role: SCHEDULER
-    group: "service-account-chromium-perf-dashboard"
+    group: "service-account-chromeperf"
   }
 }