Remove Legacy or Inactive Models

[jsotelo]

Is your feature request related to a problem? Please describe.
When a new developer attempts to familiarize themselves with the codebase, he/she will come across data models such as DeploymentInfo and CorpGroupSnapshot which are not currently used. This can lead to wasted time and confusion.

Describe the solution you'd like
Legacy or inactive data models should be removed from all subdirectories/components to make it easier to onboard new developers onto DataHub's codebase.

Describe alternatives you've considered
Alternatively, we could re-activate/fix said data models.

Additional context
Not applicable

[liangjun-jiang]

I think it is little bit too early to call DeploymentInfo and CorpGroupSnapshot legacy or inactive model. Some forks are using them .

[jsotelo]

I was informed by @keremsahin1 that DeploymentInfo was legacy via Slack. It's not linked from MCE/MAE Snapshot. How are people using it? Did they fork and linked it in themselves?

[mars-lan]

We actively use CorpGroupSnapshot internally and may open source the related code in the future. DeploymentInfo is a legacy model that will be replaced by a new entity known as DatasetInstance.