Rewrite doesRoomOrThreadHaveUnreadMessages to use the receipt rewrite from js-sdk (#11903)

* Rewrite doesRoomOrThreadHaveUnreadMessages to use the receipt rewrite from js-sdk

* Remove unit tests that rely on receipt timestamps

Previously, if we found a receipt for an unknown event, we would use the
receipt timestamp and declare all events before that time to be read.
Now, we ignore such "dangling" receipts until we find the event they
refer to.

This new behaviour is more correct, but does lead to more messages being
considered unread.

This commit deletes tests that checked for the old behaviour.

* Check for a missing thread in determineUnreadState

* Fix incorrect way to find room timeline

* More realistic test setup to support new receipt code

* Update snapshot to expect a room to be unread when there are no receipts

* Formatting fixes

* Update snapshot to show menu and notif button

* Disable some flaky tests

* Disable some flaky tests

* Fix test to make a threaded receipt for an event that is actually in the thread

---------

Co-authored-by: Florian Duros <florianduros@element.io>
Co-authored-by: Florian Duros <florian.duros@ormaz.fr>

cypress/e2e/read-receipts/high-level.spec.ts

@@ -188,7 +188,7 @@ describe("Read receipts", () => {
     });
 
     describe("Paging up", () => {
-        // Flaky test https://github.com/vector-im/element-web/issues/26437
+        // XXX: Fails because flaky test https://github.com/vector-im/element-web/issues/26437
         it.skip("Paging up through old messages after a room is read leaves the room read", () => {
             // Given lots of messages are in the room, but we have read them
             goTo(room1);