Unblacklist remove_and_bulk_insert.js concurrency workload from sharded txn suites (currently times out on slow variants)

remove_and_bulk_insert.js is a concurrency workload that alternates between bulk inserting 1000 documents into a collection and removing all documents from that collection. In the concurrency_sharded_replication_multi_stmt_txn(_with_balancer) suites, which run each state function in an fsm workload as a sharded transaction, this workload times out consistently on slow variants because of frequent write conflicts. Once the performance of sharded transactions has improved, this workload should be enabled in these suites, or if it is determined that performance will not improve enough, the workload's iterations and concurrent thread count should be reduced.