When run against an embedded router, the insert that the assert.soon() currentOp in this test is expected to trigger a CatalogCache refresh that is expected to get stuck in performNoopMajorityWriteLocally() here because the mongod is fsync locked. That is, this is the same issue as described in SERVER-83433.

The router service on mongod currently uses the ShardServerCatalogCacheLoader (SERVER-82588). So when a refresh occurs, it requires doing a noop write which will then deadlock since the mongod is fsync locked. This deadlock should go away after SERVER-82588.