The new tests cover:

• DBPrimaryRouter and CollectionRouter retry logic for various stale errors (StaleConfig, StaleDbVersion, StaleEpoch) outside of transactions. The new sub-class is added that does not initialize a session, so the OperationContext will not contain a TransactionRouter instance.
• Simple ShardNotFound error test.
• Simple TransactionParticipantFailedUnyield error test.
• Routing tests that validate correct shard targeting at specific timestamps using transaction and read concern cluster times.
• MultiCollectionRouter multi-namespace routing retry logic.
• Special case for timeseries Bucket collection namespace.