More posthog tracking around joining rooms and room search (#7807)

src/components/structures/TimelinePanel.tsx

@@ -1195,7 +1195,7 @@ class TimelinePanel extends React.Component<IProps, IState> {
                     dis.dispatch<ViewRoomPayload>({
                         action: Action.ViewRoom,
                         room_id: this.props.timelineSet.room.roomId,
-                        _trigger: undefined, // room doesn't change
+                        metricsTrigger: undefined, // room doesn't change
                     });
                 };
             }