This PR removes the usage of the custom `mongodb_proxy` package from edx-platform, replacing it with MongoDB's built-in retry functionality via `retryReads=True`. Changes: * Removed all references to `mongodb_proxy.MongoProxy` from connection logic. * Updated `connect_to_mongodb()` to always use `retryReads=True`. * Uninstalled `openedx-mongodbproxy` from edx-platform requirements. Fixes: https://github.com/openedx/edx-platform/issues/35210