### 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
if umask is not None:
        if not isinstance(umask, string_types):
            module.fail_json(msg="umask must be defined as a quoted octal integer")
        try:
            umask = int(umask, 8)
        except Exception:
            module.fail_json(msg="umask must be an octal integer",
                             details=to_text(sys.exc_info()[1]))
        os.umask(umask)
    
    
    if os.path.expanduser(repo).startswith('/'):
        repo = 'file://' + os.path.expanduser(repo)
    
    
    locale = get_best_parsable_locale(module)
    module.run_command_environ_update = dict(LANG=locale, LC_ALL=locale, LC_MESSAGES=locale, LC_CTYPE=locale)
    if separate_git_dir:
        separate_git_dir = os.path.realpath(separate_git_dir)
    gitconfig = None
    if not dest and allow_clone:
        module.fail_json(msg="the destination directory must be specified unless clone=no")
    elif dest:
        dest = os.path.abspath(dest)
        try:
            repo_path = get_repo_path(dest, bare)
            if separate_git_dir and os.path.exists(repo_path) and separate_git_dir != repo_path:
                result['changed'] = True
                if not module.check_mode: