Draft: PoC - Move only Grape API:API to the WebEngine

What does this MR do?

Based on proposed solution, we prepared PoC that is selectively loading Graphql only for Web server.

Since we got very promising numbers in Measure performance impact for proposed web_engine

We should prepare another PoC, by moving Grape API::API to the existing [web_engine] (!50180 (closed)) and measure the memory performance impact as well.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team