[CQ] Remove linux-chromeos-rel from CQ experiment

The builder has shown to be too brittle when run on dirty V8 ToT.

TBR=sergiyb@chromium.org
NOTRY=true

Bug: chromium:898965
Change-Id: I7eb1f54febeebfcc6c385cc1a9d97262f8583103
Reviewed-on: https://chromium-review.googlesource.com/c/1302056Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57046}

infra/config/cq.cfg

@@ -146,12 +146,6 @@ verifiers {
         #path_regexp: "src/api\\.cc"
         experiment_percentage: 20
       }
-      builders {
-        name: "linux-chromeos-rel"
-        #path_regexp: "include/.+\\.h"
-        #path_regexp: "src/api\\.cc"
-        experiment_percentage: 20
-      }
     }
 
     buckets {