Deprecate old DORA4 Analytics Project API

Problem

In a few months ago, we introduced an API to fetch DORA metrics at project-level. This API is functionally fine, however, it has a couple of problems:

• It frequently times out due to the inefficient aggregation approach, which causes SLA issue.
• Due to the inefficiency, we can't enable the group-level API feature flag.
• The API path (/projects/:id/analytics/deployment_frequency) is inappropriate. It should be scoped by dora.
• environment parameter should be optional as DORA metrics targets production only.
• The API design is not extensible/manageable as we have to create new path per metric.
• The cost to fix the current APIs is much more expensive than introducing new APIs, because we have to handle the breaking change carefully.

Proposal

After we've added new generic-and-performant APIs in #291746 (closed) and https://gitlab.com/gitlab-org/gitlab/-/issues/322404, we'll deprecate the old APIs. To do so, we have to change the API path in frontend at first (for project-level deployment frequency)