Make the check_migrations command a direct alias of makemigration

It already more or less was, but it previously did some machinations
around copying and modifying the database settings.  These on-the-fly
changes to the database connection no longer work after the
rearrangement of settings files, so let's just get rid of it.

awx/main/management/commands/check_migrations.py

@@ -1,13 +1,5 @@
-from django.db import connections
-from django.db.backends.sqlite3.base import DatabaseWrapper
 from django.core.management.commands.makemigrations import Command as MakeMigrations
 
 
 class Command(MakeMigrations):
-    def execute(self, *args, **options):
-        settings = connections['default'].settings_dict.copy()
-        settings['ENGINE'] = 'sqlite3'
-        if 'application_name' in settings['OPTIONS']:
-            del settings['OPTIONS']['application_name']
-        connections['default'] = DatabaseWrapper(settings)
-        return MakeMigrations().execute(*args, **options)
+    pass