Update to use LUCI for all builders

No-Try: True
Bug: 781271
Change-Id: I3f5a6e19775181cd28151634c95397834abf91bd
Reviewed-on: https://chromium-review.googlesource.com/1189135Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586103}

infra/config/branch/cq.cfg

@@ -86,13 +86,7 @@ verifiers {
       builders { name: "mac_chromium_rel_ng" }
       builders { name: "win10_chromium_x64_rel_ng" }
       builders { name: "win_chromium_compile_dbg_ng" }
-    }
-    buckets {
-      name: "master.tryserver.chromium.win"
-      builders {
-        name: "win7_chromium_rel_ng"
-        equivalent_to { bucket: "luci.chromium.try" percentage: 100 }
-      }
+      builders { name: "win7_chromium_rel_ng"}
       builders {
         name: "win7_chromium_rel_loc_exp"
         experiment_percentage: 20