The disagg standby still emits `Accepting reads after receiving checkpoint with oplog` before publishing RS_SECONDARY. Commands with maintenanceOk=false (listCollections among them) are refused with NotPrimaryOrSecondary until the member state is SECONDARY, so tests that gate standby reads on that log line can still hit the race that SERVER-131887 narrowed. Emit the log only after the RS_SECONDARY publish and pin the ordering in the unit test.