MXSpaceServiceTest: Update MXSpace.addChild calls and add missing XCTExpectation.fulfill() calls.
MXSpaceServiceTest: Update MXSpace.addChild calls and add missing XCTExpectation.fulfill() calls.

matrix-org/matrix-ios-sdk,matrix-org/matrix-ios-sdk,matrix-org/matrix-ios-sdk,matrix-org/matrix-ios-sdk,matrix-org/matrix-ios-sdk