Remove some obsolete code.

pytest.ini

@@ -7,6 +7,5 @@ addopts = --reuse-db --nomigrations --tb=native
 markers =
     ac: access control test
     license_feature: ensure license features are accessible or not depending on license
-    mongo_db: drop mongodb test database before test runs
     survey: tests related to survey feature
     inventory_import: tests of code used by inventory import command