recover_prepared_transactions_startup_secondary_application.js and prepare_transaction_index_build.js need to use PrepareHelpers.prepareTransaction with w: 1 to test prepare recovery/index build blocking prepared transactions on secondaries. Instead of using awaitReplication which doesn't necessarily align with the primary's local view of majority committed point, we should check lastCommittedOpTime on primary to make sure the majority commit point has been advanced past the prepareTimstamp.