[cq] Update configuration.

Authorize people with try-job access to do dry runs.
Change to faster blink trybot in 20% experiment.

NOTRY=true
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1692943002

Cr-Commit-Position: refs/heads/master@{#33950}

infra/config/cq.cfg

@@ -16,6 +16,7 @@ rietveld {
 verifiers {
   reviewer_lgtm {
     committer_list: "project-v8-committers"
+    dry_run_access_list: "project-v8-tryjob-access"
   }
 
   tree_status {
@@ -66,9 +67,9 @@ verifiers {
       }
     }
     buckets {
-      name: "tryserver.blink"
+      name: "tryserver.v8"
       builders {
-        name: "linux_blink_rel"
+        name: "v8_linux_blink_rel"
         experiment_percentage: 20
       }
     }