New Room List: Prevent old tombstoned rooms from appearing in the list (#29881)

* Write failing playwright test

Basically when someone changes their name, any old tombstoned rooms that
were previously hidden would suddenly show up in the list.

* Split addRoom into two methods

- `reInsertRoom` that re-inserts a room that is already known by the skiplist.
- `addNewRoom` to add new rooms

The idea is that sometimes you only want to re-insert to noop, eg: when
you get an event in an old room that was upgraded.

* Use new methods in the RLS

Only use `addNewRoom` when absolutely necessary. Most events should
instead use `reInsertRoom` which will noop when the room isn't already
known by the skiplist.

* Fix broken tests

* Add new test

* Fix playwright test

playwright/e2e/left-panel/room-list-panel/room-list-filter-sort.spec.ts

@@ -5,8 +5,11 @@
  * Please see LICENSE files in the repository root for full details.
  */
 
+import { type Visibility } from "matrix-js-sdk/src/matrix";
+import { type Locator, type Page } from "@playwright/test";
+
 import { expect, test } from "../../../element-web-test";
-import type { Locator, Page } from "@playwright/test";
+import { SettingLevel } from "../../../../src/settings/SettingLevel";
 
 test.describe("Room list filters and sort", () => {
     test.use({
@@ -39,6 +42,65 @@ test.describe("Room list filters and sort", () => {
         await app.closeNotificationToast();
     });
 
+    test("Tombstoned rooms are not shown even when they receive updates", async ({ page, app, bot }) => {
+        // This bug shows up with this setting turned on
+        await app.settings.setValue("Spaces.allRoomsInHome", null, SettingLevel.DEVICE, true);
+
+        /*
+        We will first create a room named 'Old Room' and will invite the bot user to this room.
+        We will also send a simple message in this room.
+        */
+        const oldRoomId = await app.client.createRoom({ name: "Old Room" });
+        await app.client.inviteUser(oldRoomId, bot.credentials.userId);
+        await bot.joinRoom(oldRoomId);
+        const response = await app.client.sendMessage(oldRoomId, "Hello!");
+
+        /*
+        At this point, we haven't done anything interesting.
+        So we expect 'Old Room' to show up in the room list.
+        */
+        const roomListView = getRoomList(page);
+        const oldRoomTile = roomListView.getByRole("gridcell", { name: "Open room Old Room" });
+        await expect(oldRoomTile).toBeVisible();
+
+        /*
+        Now let's tombstone 'Old Room'.
+        First we create a new room ('New Room') with the predecessor set to the old room..
+        */
+        const newRoomId = await bot.createRoom({
+            name: "New Room",
+            creation_content: {
+                predecessor: {
+                    event_id: response.event_id,
+                    room_id: oldRoomId,
+                },
+            },
+            visibility: "public" as Visibility,
+        });
+
+        /*
+        Now we can send the tombstone event itself to the 'Old Room'.
+        */
+        await app.client.sendStateEvent(oldRoomId, "m.room.tombstone", {
+            body: "This room has been replaced",
+            replacement_room: newRoomId,
+        });
+
+        // Let's join the replaced room.
+        await app.client.joinRoom(newRoomId);
+
+        // We expect 'Old Room' to be hidden from the room list.
+        await expect(oldRoomTile).not.toBeVisible();
+
+        /*
+        Let's say some user in the 'Old Room' changes their display name.
+        This will send events to the all the rooms including 'Old Room'.
+        Nevertheless, the replaced room should not be shown in the room list.
+        */
+        await bot.setDisplayName("MyNewName");
+        await expect(oldRoomTile).not.toBeVisible();
+    });
+
     test.describe("Scroll behaviour", () => {
         test("should scroll to the top of list when filter is applied and active room is not in filtered list", async ({
             page,