chore(controller): move grants schema route to internal

[bgajjala8]

Description

This PR moves /grants-schema.json to /internal/grants-schema.json to reflect that it is an internal only endpoint not intended for public consumption.

PCI review checklist

• I have documented a clear reason for, and description of, the change I am making.
• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.
• If applicable, I've documented the impact of any changes to security controls.
  Examples of changes to security controls include using new access control methods, adding or removing logging pipelines, etc.

[ZedLi]

Worked for me!