New setting for TTL for the dependency proxy

Context

In #294187 (closed), we added a GraphQL API to CRUD a new time-to-life policy for container images that have been pulled from Docker Hub using the GitLab Dependency Proxy. This policy allows Group Admin to automatically remove items from the Dependency Proxy cache on a regular cadence.

This helps to reduce storage costs and keep the cache fresh.

Problem to solve

The problem is that there is no where in the user interface for you to define/update these TTL policies.

Proposal

Once the settings for the dependency proxy have been moved to the settings page (#322841 (closed)), we will add a new flow to the dependency proxy settings that allows Group Admin to CRUD TTL policies for the dependency proxy.

The default TTL for all groups should be 90 days.

Further details

With the API, you can choose to have the policy enabled or disabled and the number of days to retain a cached image file. Add a UI that allows you to do the same.

• ❓ should we allow the user to enter any valid integer or should we give them options similar to the cleanup policies?

Name	Type	Description
createdAt	Time	Timestamp of creation.
enabled	Boolean!	Indicates whether the policy is enabled or disabled.
ttl	Int	Number of days to retain a cached image file.
updatedAt	Time	Timestamp of the most recent update.

Documentation

• Ensure the dependency proxy Admin documentation is updated