Sort the pinning message list in the same order than the banner (#12937)

test/components/views/right_panel/PinnedMessagesCard-test.tsx

@@ -165,12 +165,14 @@ describe("<PinnedMessagesCard />", () => {
         room: "!room:example.org",
         user: "@alice:example.org",
         msg: "First pinned message",
+        ts: 2,
     });
     const pin2 = mkMessage({
         event: true,
         room: "!room:example.org",
         user: "@alice:example.org",
         msg: "The second one",
+        ts: 1,
     });
 
     it("should show spinner whilst loading", async () => {