Fix clicking on copy link to thread wrongly opening thread (#8038)

Author: t3chguy

src/components/views/rooms/EventTile.tsx

@@ -656,6 +656,8 @@ export class UnwrappedEventTile extends React.Component<IProps, IState> {
     };
 
     private copyLinkToThread = async (evt: ButtonEvent): Promise<void> => {
+        evt.preventDefault();
+        evt.stopPropagation();
         const { permalinkCreator, mxEvent } = this.props;
         const matrixToUrl = permalinkCreator.forEvent(mxEvent.getId());
         await copyPlaintext(matrixToUrl);