Improve composer visiblity (#8578)

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

test/components/views/rooms/MessageComposer-test.tsx

@@ -61,7 +61,7 @@ describe("MessageComposer", () => {
 
         expect(wrapper.find("SendMessageComposer")).toHaveLength(0);
         expect(wrapper.find("MessageComposerButtons")).toHaveLength(0);
-        expect(wrapper.find(".mx_MessageComposer_roomReplaced_header")).toHaveLength(1);
+        expect(wrapper.find("p").text()).toContain("room has been replaced");
     });
 });