When FunctionalTestCase::getUri() prohibits multi-mongos URIs (default behavior) but encounters a MONGODB_URI with an SRV scheme (i.e. not "mongodb://"), it returns the URI as-is.

This has yet to cause test failures but it seems incorrect. For a replica set topology, the SRV URI can be used as-is but for a sharded topology it will most certainly point to multiple mongoses (assuming we're using Atlas). In this case, we can probably defer addressing this until we test sharded clusters on Atlas.