Playwright: Fix thread root skipped tests (#12067)

* Fix thread root skipped tests

* Add comment about collapsed content in `redactions.spec.ts`

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Co-authored-by: David Baker <dbkr@users.noreply.github.com>

playwright/e2e/read-receipts/index.ts

@@ -370,6 +370,15 @@ class Helpers {
         await this.app.viewRoomByName(typeof room === "string" ? room : room.name);
     }
 
+    /**
+     * Expand the message with the supplied index in the timeline.
+     * @param index
+     */
+    async openCollapsedMessage(index: number) {
+        const button = this.page.locator(".mx_GenericEventListSummary_toggle");
+        await button.nth(index).click();
+    }
+
     /**
      * Click the thread with the supplied content in the thread root to open it in
      * the Threads panel.