logout route at multiple places

**Describe the enhancement you'd like**
Currently, there are two logout routes and controllers which is certainly unnecessary!
https://github.com/codeuino/social-platform-donut-backend/blob/b59ccca19cd0f44ffe10e59da456cd3546be61df/app/routes/user.js#L76
https://github.com/codeuino/social-platform-donut-backend/blob/b59ccca19cd0f44ffe10e59da456cd3546be61df/app/routes/auth.js#L14

**Describe approaches if you have thought of any**
Remove any of those unless there's a valid reason to keep both. If we've to keep both, mention the same in code comments.

**Additional context**
NA