CreateKeyBackupDialog.tsx: Remove logic for servers which are not supporting cross-signing (#11076)

test/test-utils/test-utils.ts

@@ -157,6 +157,7 @@ export function createTestClient(): MatrixClient {
             });
         }),
         mxcUrlToHttp: (mxc: string) => `http://this.is.a.url/${mxc.substring(6)}`,
+        scheduleAllGroupSessionsForBackup: jest.fn().mockResolvedValue(undefined),
         setAccountData: jest.fn(),
         setRoomAccountData: jest.fn(),
         setRoomTopic: jest.fn(),