Spike: Disable policies and cleanup records in database after downgrading license from Ultimate

Time-box: 2 days

Why are we doing this work

In the scope of this small Spike, we would like to verify what we should do to disable policies and cleanup all records in database after downgrading licenses from Ultimate. We want to ensure everything is either disabled, cleared or turned off to ensure that other GitLab features are working as expected.

As an expected result of this Spike, we would like to get the following:

• PoC MR with proposed changes for backend (GraphQL API, database changes, etc.) or initial plan how to implement it,
• implementation issues for backend,