### Summary

For some modules, notably the `package` module, Ansible relies on the `ansible_pkg_mgr" fact to decide which package manager it should be using.

On systems where `rpm-ostree` is present at `/usr/bin/rpm-ostree`, Ansible makes the assumption that the system's dominant package manager is `rpm-ostree` and returns `atomic_container` as the entry for the `ansible_pkg_mgr` fact.

This isn't always a safe assumption to make, however. On systems with [OSBuild](https://www.osbuild.org/) installed, particularly OSBuild Composer, there's a dependency tree that leads to `rpm-ostree` being pulled in.

You can see this by installing the RHEL 8 / CentOS 8 / Rocky 8 package `osbuild-composer`. It has a dependency on `osbuild-ostree`, which in turn depends on `rpm-ostree`.

So I have quite a few (standard, `dnf`-based) RHEL and Rocky systems which do have `/usr/bin/rpm-ostree` present for legitimate reasons, but not as the dominant package manager.

This is reproducible in 2.9.20 and 2.10.9. I haven't tried other versions but the problem is still present in the code in the devel branch.

### Issue Type

Bug Report

### Component Name

pkg_mgr.py

### Ansible Version

```console
╰─ ansible --version 
ansible 2.10.9
  config file = None
  configured module search path = ['/home/user/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python3.6/site-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 3.6.8 (default, Apr 12 2021, 07:42:28) [GCC 8.3.1 20191121 (Red Hat 8.3.1-5)]
```


### Configuration

```console
╰─ ansible-config dump --only-changed
ANSIBLE_NOCOWS(env: ANSIBLE_NOCOWS) = True
```


### OS / Environment

RHEL 8, Rocky 8

### Steps to Reproduce

```sh
╰─ ansible -m setup localhost | grep pkg
        "ansible_pkg_mgr": "dnf",
```

```sh
╰─ sudo dnf install osbuild-composer -y
[...]
(or any package that depends on rpm-ostree)
[...]
```

```sh
╰─ ansible -m setup localhost | grep pkg
        "ansible_pkg_mgr": "atomic_container",
```

### Expected Results

The ansible_pkg_mgr fact should not change just because rpm-ostree is installed. It should only change if the host's actual package manager is ostree.

### Actual Results

```console
The ansible_pkg_mgr fact changes just because rpm-ostree is installed.
```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
pkg_mgr_name = 'yum'
        else:
            
            
            
            
            
            
            if int(collected_facts['ansible_distribution_major_version']) < 8:
                pkg_mgr_name = 'yum'
            else:
                pkg_mgr_name = 'dnf'
        return pkg_mgr_name
    def _check_apt_flavor(self, pkg_mgr_name):
        
        
        
        
        rpm_query = '/usr/bin/rpm -q --whatprovides /usr/bin/apt-get'.split()
        if os.path.exists('/usr/bin/rpm'):
            with open(os.devnull, 'w') as null:
                try:
                    subprocess.check_call(rpm_query, stdout=null, stderr=null)
                    pkg_mgr_name = 'apt_rpm'
                except subprocess.CalledProcessError:
                    
                    
                    pkg_mgr_name = 'apt'
        return pkg_mgr_name
    def collect(self, module=None, collected_facts=None):