### Summary

To reproduce, run these commands where `ns.col` is the name of a collection you do not have installed and the value of `-p` is a valid collection path that exists:

`ansible-galaxy collection list ns.col -p collections/`
`$?`

The output of $? on devel is 0, but since the collection wasn't found it should be 1. The same issue exists for listing specific roles that do not exist.

To fix:
1. [This method](https://github.com/ansible/ansible/blob/stable-2.14/lib/ansible/cli/galaxy.py#L1494-L1502) needs to return the correct exit code from `execute_list_role` and `execute_list_collection`.

2. `execute_list_collection` and `execute_list_role` will need to be fixed to return 1 if a collection/role was requested and not found.
For example, on [this line ](https://github.com/ansible/ansible/blob/stable-2.14/lib/ansible/cli/galaxy.py#L1680) add
```python
        if not collection_found and collection_name:
            return 1
```

3. Add a new test to [this file](https://github.com/ansible/ansible/blob/stable-2.14/test/integration/targets/ansible-galaxy-collection/tasks/list.yml), similar to [this one](https://github.com/ansible/ansible/blob/stable-2.14/test/integration/targets/ansible-galaxy-collection/tasks/list.yml#L111-L116) that lists a single collection that does not exist. Then add an assert task following it to test that the command result's rc is 1.

4. Add a `bugfixes` [changelog fragment](https://docs.ansible.com/ansible/latest/community/development_process.html#creating-a-changelog-fragment).

### Issue Type

Bug Report

### Component Name

ansible-galaxy

### Ansible Version

```console
$ ansible --version
ansible [core 2.15.0.dev0]
```


### Configuration

```console
# if using a version older than ansible-core 2.12 you should omit the '-t all'
$ ansible-config dump --only-changed -t all
```


### OS / Environment

N/A

### Steps to Reproduce

<!--- Paste example playbooks or commands between quotes below -->
```bash (paste below)
ansible-galaxy collection list ns.col -p collections/
$?
```

### Expected Results

1

### Actual Results

```console
0
```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
disable_gpg_verify = context.CLIARGS['disable_gpg_verify']
        except KeyError:
            if self._implicit_role:
                raise AnsibleError(
                    'Unable to properly parse command line arguments. Please use "ansible-galaxy collection install" '
                    'instead of "ansible-galaxy install".'
                )
            raise
        
        allow_pre_release = context.CLIARGS.get('allow_pre_release', False)
        upgrade = context.CLIARGS.get('upgrade', False)
        collections_path = C.COLLECTIONS_PATHS
        if len([p for p in collections_path if p.startswith(path)]) == 0:
            display.warning("The specified collections path '%s' is not part of the configured Ansible "
                            "collections paths '%s'. The installed collection will not be picked up in an Ansible "
                            "run, unless within a playbook-adjacent collections directory." % (to_text(path), to_text(":".join(collections_path))))
        output_path = validate_collection_path(path)
        b_output_path = to_bytes(output_path, errors='surrogate_or_strict')
        if not os.path.exists(b_output_path):
            os.makedirs(b_output_path)
        install_collections(
            requirements, output_path, self.api_servers, ignore_errors,
            no_deps, force, force_with_deps, upgrade,
            allow_pre_release=allow_pre_release,
            artifacts_manager=artifacts_manager,
            disable_gpg_verify=disable_gpg_verify,
            offline=context.CLIARGS.get('offline', False),
        )
        return 0
    def _execute_install_role(self, requirements):