Run zucchini_unittests on "Win10 Tests x64"

It's not clear why this should run on all bots except this one.

Bug: 843511
Change-Id: I354c78445c1f64de2b8bf27f18fd60a2081fd726
Reviewed-on: https://chromium-review.googlesource.com/1120229
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571495}

testing/buildbot/chromium.win.json

@@ -1324,6 +1324,12 @@
           "can_use_on_swarming_builders": true
         },
         "test": "wtf_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "zucchini_unittests"
       }
     ],
     "isolated_scripts": [

testing/buildbot/test_suite_exceptions.pyl

@@ -2986,10 +2986,4 @@
       'Win 10 Fast Ring',
     ],
   },
-  'zucchini_unittests': {
-    'remove_from': [
-      # chromium.win
-      'Win10 Tests x64',
-    ],
-  },
 }