### 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
""" Setup an integration from Github or Travis for Ansible Galaxy roles"""
        if context.CLIARGS['setup_list']:
            
            secrets = self.api.list_secrets()
            if len(secrets) == 0:
                
                display.display("No integrations found.")
                return 0
            display.display(u'\n' + "ID         Source     Repo", color=C.COLOR_OK)
            display.display("---------- ---------- ----------", color=C.COLOR_OK)
            for secret in secrets:
                display.display("%-10s %-10s %s/%s" % (secret['id'], secret['source'], secret['github_user'],
                                                       secret['github_repo']), color=C.COLOR_OK)
            return 0
        if context.CLIARGS['remove_id']:
            
            self.api.remove_secret(context.CLIARGS['remove_id'])
            display.display("Secret removed. Integrations using this secret will not longer work.", color=C.COLOR_OK)
            return 0
        source = context.CLIARGS['source']
        github_user = context.CLIARGS['github_user']
        github_repo = context.CLIARGS['github_repo']
        secret = context.CLIARGS['secret']
        resp = self.api.add_secret(source, github_user, github_repo, secret)
        display.display("Added integration for %s %s/%s" % (resp['source'], resp['github_user'], resp['github_repo']))
        return 0
    def execute_delete(self):