Move security dashboard CSS into ee SCSS file

- there is a SCSS file that already exists. Moved
  my new CSS into there

app/assets/stylesheets/pages/security_dashboard.scss

-.security_dashboard_filters {
-  top: $header-height;
-
-  .with-performance-bar & {
-    top: $header-height + $performance-bar-height;
-  }
-}

ee/app/assets/stylesheets/pages/security_dashboard.scss

@@ -23,3 +23,10 @@
   }
 }
 
+.security_dashboard_filters {
+  top: $header-height;
+
+  .with-performance-bar & {
+    top: $header-height + $performance-bar-height;
+  }
+}