Remove ability to create new contxt-managed services from the CLI

[kkikendall]

Why?

• JIRA: Remove contxt-managed service creation

What changed?

• Remove contxt-managed as an option.

[kkikendall]

I realize that removing this from the CLI does not prevent people with older versions of the CLI from creating contxt-managed entities. We really need to also update the API to remove this feature, but first, I think we need confirmation that this is really a product-wide desired change.