### Summary

See: https://github.com/ansible/ansible/blob/devel/lib/ansible/modules/git.py#L760 :

```py
            repo_path = os.path.join(repo_path.split('.git')[0], gitdir)
```

the intention of this code seems to be to strip `.git` from the end of the path.

If the repo path contains `.git` anywhere, like `/tmp/music.gittern/myrepo`, tasks will unexpectedly fail:

```
fatal: [localhost]: FAILED! => {"changed": false, "details": "/tmp/music/../.git/modules/submodule is not a directory", "msg": "Current repo does not have a valid reference to a separate Git dir or it refers to the invalid path"}
```

For a playbook like:
```yaml
---
- hosts: localhost
  tasks:
   - name: test git
     git: 
        repo: ...
        dest: /tmp/music.gittern/myrepo/submodule
```

I can't tell if this is a potential security issue or just an unexpected corner case. What I am pretty sure I can tell, is that that's not how one strips `.git` from the end of a path.

### Issue Type

Bug Report

### Component Name

git

### Ansible Version

```console
$ ansible --version
2.11
```


### Configuration

```console
$ ansible-config dump --only-changed
ANSIBLE_NOCOWS(/home/enrico/dev/transilience/ansible.cfg) = True
```


### OS / Environment

Debian Bullseye

### Steps to Reproduce

Use submodules in a repo whose path contains `.git` anywhere as part of a file name.
For example:
```yaml
---
- hosts: localhost
  tasks:
   - name: test git
     git: 
        repo: ...
        dest: /tmp/music.gittern/myrepo/submodule
```

### Expected Results

I'd expect directory names like `gato.gito` not to be interpreted specially by mistake

### Actual Results

```console
fatal: [localhost]: FAILED! => {"changed": false, "details": "/tmp/music/../.git/modules/submodule is not a directory", "msg": "Current repo does not have a valid reference to a separate Git dir or it refers to the invalid path"}
```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
cmd = [git_path, 'submodule', 'status']
            (rc, out, err) = module.run_command(cmd, check_rc=True, cwd=dest)
            if rc != 0:
                module.fail_json(msg='Failed to retrieve submodule status: %s' % out + err)
            for line in out.splitlines():
                if line[0] != ' ':
                    changed = True
                    break
    return changed
def submodule_update(git_path, module, dest, track_submodules, force=False):
    ''' init and update any submodules '''
    
    params = get_submodule_update_params(module, git_path, dest)
    
    if not os.path.exists(os.path.join(dest, '.gitmodules')):
        return (0, '', '')
    cmd = [git_path, 'submodule', 'sync']
    (rc, out, err) = module.run_command(cmd, check_rc=True, cwd=dest)
    if 'remote' in params and track_submodules:
        cmd = [git_path, 'submodule', 'update', '--init', '--recursive', '--remote']
    else:
        cmd = [git_path, 'submodule', 'update', '--init', '--recursive']
    if force:
        cmd.append('--force')
    (rc, out, err) = module.run_command(cmd, cwd=dest)
    if rc != 0:
        module.fail_json(msg="Failed to init/update submodules: %s" % out + err)
    return (rc, out, err)
def set_remote_branch(git_path, module, dest, remote, version, depth):