sharded_collections_jscore_passthrough_with_config_transitions transitions from/to config shard and dedicated config server. Transitioning from a config shard requires draining that shard. If there are sharded collections, this requires moving the chunks away from that shard.

There are at least 85 tests under jstests/core that issue dropIndexes('*'), which since SERVER-78253 also drops the hashed shard key index. This prevents chunk migrations from succeeding, so the shard drain fails, which causes the config transitions to fail.