feat!: Drop management commands that depend on the snowflake connector

This work is a part of https://github.com/openedx/edx-enterprise/issues/2467

BREAKING CHANGE: The monthly_impact_report and nudge_dormant_enrolled_enterprise_learners
management commands will no longer be available here. If you need these
commands, you can copy them to a plugin that is not required to be
installed in the edx-platform