Mark Windows CQ builder as experimental

The builder will still build and test all changes but the the outcome
does not affect the decicion whether a CL can land or not. This is only
temporary until Windows builder is actually usable.

Change-Id: I58dee15cec443667b0764c7379af32828aceb225
Reviewed-on: https://gn-review.googlesource.com/1404
Reviewed-by: Scott Graham <scottmg@chromium.org>

infra/config/cq.cfg

diff --git a/infra/config/cq.cfg b/infra/config/cq.cfg
index bb3a274..99a5c22 100644
--- a/infra/config/cq.cfg
+++ b/infra/config/cq.cfg
@@ -17,6 +17,7 @@
       }
       builders {
         name: "win"
+        experiment_percentage: 100
       }
     }
   }