Upgrade pymongo to 4.2.0

This is a non trivial upgrade since our infrastructure relies heavily on pymongo.

buildscripts/resmokelib/testing/fixtures/standalone.py
^ changing the above file by replacing...
return "mongodb://" + self.get_internal_connection_string()
with...
return "mongodb://" + self.get_internal_connection_string() + "/?directConnection=true"
 
makes most tests pass, but there are still ~100 test failures on required builders at the moment

https://evergreen.mongodb.com/filediff/63470ab21e2d176fcffcec16/?file_name=buildscripts%2Fresmokelib%2Ftesting%2Ffixtures%2Fstandalone.py&patch_number=0