Get rid of @override.

- Remove superfluous @override.
- Replace @override with override
- Get rid of empty overridden method in
  `polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content.ts`

Change-Id: Ibcf63c0d1d22e64abd36323f371549e56eee7e23
diff --git a/polygerrit-ui/app/elements/change-list/gr-change-list-view/gr-change-list-view.ts b/polygerrit-ui/app/elements/change-list/gr-change-list-view/gr-change-list-view.ts
index 84bc1e2..9970dd5 100644
--- a/polygerrit-ui/app/elements/change-list/gr-change-list-view/gr-change-list-view.ts
+++ b/polygerrit-ui/app/elements/change-list/gr-change-list-view/gr-change-list-view.ts
@@ -118,8 +118,7 @@
     this.addEventListener('previous-page', () => this._handlePreviousPage());
   }
 
-  /** @override */
-  connectedCallback() {
+  override connectedCallback() {
     super.connectedCallback();
     this._loadPreferences();
   }