Update Package maturity targets November 2020

Why is this change being made?

This MR proposes updating the maturity targets for the Package stage.

Changes

• Moves back the date of the Dependency Proxy for reaching Complete. This is because the scope of the category has changed over the past several months. In my earlier maturity targets I focused primarily on caching images from Docker Hub. But, based on customer demand, it's clear that the proxy should support all package manager formats. This includes supporting remote and virtual registries for npm, maven, pypi and nuget. This work can be found in this epic: gitlab-org&2614 (closed)
• Moves back the maturity targets for Release evidence. The Package group recently took on this category and given our current roadmap, this will be lower in priority than helping customers to migrate off of Artifactory.

Questions

• What should we do with the GitLFS maturity target?

Author Checklist

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