Revert "[ios] Reenable iOS cq bots at 100% experiment."

This reverts commit 8a3426a.

Reason for revert: large pending queue on the tryserver

Original change's description:
> [ios] Reenable iOS cq bots at 100% experiment.
> 
> Collecting more capacity info.
> 
> Bug: 740301
> Change-Id: I475e06b5423e060dc7808f628f9a3fea3b6b4d1b
> Reviewed-on: https://chromium-review.googlesource.com/583288
> Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> Commit-Queue: John Budorick <jbudorick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#489284}

TBR=smut@google.com,dpranke@chromium.org,jbudorick@chromium.org

Change-Id: I155b5f014aac28d3e5f3db4fe3a769487ae494eb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 740301
Reviewed-on: https://chromium-review.googlesource.com/585488
Reviewed-by: Benjamin Pastene <bpastene@chromium.org>
Commit-Queue: Benjamin Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489402}

infra/config/cq.cfg

@@ -73,16 +73,9 @@ verifiers {
         experiment_percentage: 100
       }
       # https://crbug.com/739556
-      builders {
-        name: "ios-device-xcode-clang"
-        experiment_percentage: 100
-      }
+      # builders { name: "ios-device-xcode-clang" }
       builders { name: "ios-simulator" }
-      # https://crbug.com/739556
-      builders {
-        name: "ios-simulator-xcode-clang"
-        experiment_percentage: 100
-      }
+      # builders { name: "ios-simulator-xcode-clang" }
       builders { name: "mac_chromium_compile_dbg_ng" }
       builders { name: "mac_chromium_rel_ng" }
     }