[cq] Get codereview coverage bot's experiment percentage back to 100

Resources reduced after:
https://chromium-review.googlesource.com/c/474753/

BUG: chromium:568949
NOTRY=true
TBR=tandrii@chromium.org

Change-Id: I3c88ebfe906857d664ea30e0247ed911c6819747
Reviewed-on: https://chromium-review.googlesource.com/474148
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44580}

infra/config/cq.cfg

@@ -123,7 +123,7 @@ verifiers {
       }
       builders {
         name: "v8_linux64_sanitizer_coverage_rel"
-        experiment_percentage: 20
+        experiment_percentage: 100
       }
     }
     buckets {