[Monorepo] Cleanup Redundant Files and Scripts

- Removed `check-go-version.sh` from `catalogd/hack/scripts` as it is no longer needed.
  - Both projects now rely on the `go.mod` file at the root directory for Go version checks.

- Removed duplicated files from the repository:
  - `CODEOWNERS`
  - `CONTRIBUTING.md`
  - `DOC`
  - `LICENSE.md`

- Use hack/boilerplate.go.txt from root and remove duplication

Author: camilamacedo86