cabal commands show git output

**Describe the bug**
Running some cabal commands shows the git output when `source-repository-package` stanzas are present. This is particularly bothersome when doing

```bash
MY_EXE="$(cabal list-bin my-exe)"
```

which captures git output in `MY_EXE`. At the very least, the git output should be redirected into stderr.

Possibly new behavior with 3.10.

**To Reproduce**
Steps to reproduce the behavior:

1. Add `source-repository-package` to `cabal.project`
2. `rm -rf dist-newstyle`
3. `EXE="$(cabal list-bin some-exe)"`
4. `echo $EXE` shows `HEAD is now at ...`

**Expected behavior**
git output should be in stderr

**System information**
- Operating system
- `cabal`, `ghc` versions

**Additional context**
Add any other context about the problem here.