get rid of more memberhsip manager usage in tests

Author: toger5

spec/unit/matrixrtc/MatrixRTCSession.spec.ts

@@ -486,10 +486,7 @@ describe("MatrixRTCSession", () => {
                     membershipServerSideExpiryTimeout: 9000,
                 });
 
-                expect((sess as any).membershipManager).toHaveProperty("membershipServerSideExpiryTimeout", 9000);
                 await sendDelayedStateExceedAttempt.then(); // needed to resolve after the send attempt catches
-                expect((sess as any).membershipManager).toHaveProperty("membershipServerSideExpiryTimeout", 7500);
-
                 await sendDelayedStateAttempt;
                 const callProps = (d: number) => {
                     return [mockRoom!.roomId, { delay: d }, "org.matrix.msc3401.call.member", {}, userStateKey];