Add feedback to user when trying to push to a project scheduled for deletion
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=344023)
</details>
<!--IssueSummary end-->
## Problem to solve
When a user tries to push to a repo, they get a response message about not being allowed to push but it is not explained why.
## Proposal
Update the message sent back to the user in terminal sessions
**Before**
```
> git push
remote: You are not allowed to push code to this project.
fatal: unable to access 'http://127.0.0.1:3000/group/project.git/': The requested URL returned error: 403
```
**After**
```
> git push
remote: You are not allowed to push code to this project. This project is read-only and will be deleted on YYYY-MM-DD.
fatal: unable to access 'http://127.0.0.1:3000/group/project.git/': The requested URL returned error: 403
```
issue