Remove misplaced "selector" field

This CL is part of a larger refactoring/clean-up of
policy_test_cases.json.

The field only exists as part of the "indicator_tests" so it is ignored
here.

Bug: 1151251
Change-Id: I6ff4ff8b88c4befaa7b340000fd149c5ea206f5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2550819Reviewed-by: Pavol Marko <pmarko@chromium.org>
Commit-Queue: Alexander Hendrich <hendrich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#830235}

chrome/test/data/policy/policy_test_cases.json

@@ -3227,8 +3227,7 @@
             "url": "http://localhost/",
             "hash": "deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef"
           }
-        },
-        "selector": "#account-picture-indicator"
+        }
       }
     ]
   },
@@ -3242,8 +3241,7 @@
             "url": "http://localhost/",
             "hash": "baddecafbaddecafbaddecafbaddecafbaddecafbaddecafbaddecafbaddecaf"
           }
-        },
-        "selector": "#wallpaper-indicator"
+        }
       }
     ]
   },