Fix/refactor-and-cleanup

[anuragkainth]

• Moved ORIGIN_OWNER_ID & ORIGIN_OWNER_NAME to backend environment variables.
• Fixed error handling in the backend.
• Replaced id with remote_id in job view.
• Replaced job_id and candidate_id with remote_job_id and remote_candidate_id in application view.
• Removed unwanted files.
• Other code refactorings for improved maintainability and readability.

[glebedel]

LGTM