Revert "[cq.cfg] Make ios-simulator 100% experimental"

This reverts commit 5cf8deb5.

Reason for revert:

After cleaning up the unused Xcode versions and iOS runtime versions, disk usage has dropped to around 80%. Putting ios-simulator back to CQ.

Original change's description:
> [cq.cfg] Make ios-simulator 100% experimental
> 
> Unfortunately this builder seems to have a recipe bug with
> analyze and the way it runs one of the test suites.
> 
> R=​jchinlee@chromium.org, tandrii@chromium.org
> TBR=jbudorick@chromium.org
> 
> Bug: 832483
> Change-Id: I64d774535b52a92981a597d6c23e45659ae6aae1
> Reviewed-on: https://chromium-review.googlesource.com/1011825
> Reviewed-by: Jao-ke Chin-Lee <jchinlee@chromium.org>
> Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#550512}

TBR=iannucci@chromium.org,jchinlee@chromium.org,tandrii@chromium.org,jbudorick@chromium.org

Change-Id: Ib83e5589367de8b0d698dd614f5a3ddeaf56aff8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 832434
Reviewed-on: https://chromium-review.googlesource.com/1012819Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550764}

infra/config/branch/cq.cfg

@@ -141,11 +141,7 @@ verifiers {
       }
       builders {
         name: "ios-simulator"
-        # https://crbug.com/832483
-        # Unfortunately experiment_percentage is mutually exclusive with
-        # equivalent_to, so that's commented out for now.
-        # equivalent_to { bucket: "luci.chromium.try" percentage: 0 }
-        experiment_percentage: 100
+        equivalent_to { bucket: "luci.chromium.try" percentage: 0 }
       }
       # https://crbug.com/739556
       builders {