Assert that the thread is unread after an edit (#11504)

* Expand a thread reply test to be more explicit

* Add an assertion that the thread is read after I read it

* Assert that the thread is unread after an edit

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

@@ -103,6 +103,11 @@ describe("Read receipts", () => {
         });
     }
 
+    function backToThreadsList() {
+        cy.log("Back to threads list");
+        cy.get(".mx_RightPanel").findByTitle("Threads").click();
+    }
+
     /**
      * Find and display a message.
      *
@@ -391,11 +396,6 @@ describe("Read receipts", () => {
         });
     }
 
-    function backToThreadsList() {
-        cy.log("Back to threads list");
-        cy.get(".mx_RightPanel").findByTitle("Threads").click();
-    }
-
     function openThreadList() {
         cy.log("Open threads list");
         cy.findByTestId("threadsButton", { log: false }).then(($button) => {
@@ -1000,6 +1000,7 @@ describe("Read receipts", () => {
                 goTo(room2);
                 openThread("Msg1");
                 assertRead(room2);
+                backToThreadsList();
                 goTo(room1);
 
                 // When a message inside it is edited