### Summary

When running `ansible -m setup host`, reported `ansible_memtotal_mb` fact changes between invocations.
That's because `setup` reads available non-kernel memory, which fluctuates:

https://github.com/ansible/ansible/blob/2797dc644aa8c809444ccac64cad63e0d9a3f9fe/lib/ansible/module_utils/facts/hardware/openbsd.py#L96-L97

To read total available memory, `hw.physmem` key should be used. Refer to the https://man.openbsd.org/sysctl.2 man, `HW_USERMEM` and `HW_PHYSMEM`.

### Issue Type

Bug Report

### Component Name

setup

### Ansible Version

```console
All.

https://github.com/ansible/ansible/blob/devel/lib/ansible/module_utils/facts/hardware/openbsd.py#L97
```


### Configuration

```console
N/A
```


### OS / Environment

OpenBSD 7.0

### Steps to Reproduce

On OpenBSD host, run this few times:

```
ansible -m setup openbsd_host | grep memtotal
```

Total memory value will be fluctuation between calls.

### Expected Results

I expect to see total installed memory.

### Actual Results

```console
N/A
```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
#
#
#
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
import re
import time
from ansible.module_utils._text import to_text
from ansible.module_utils.facts.hardware.base import Hardware, HardwareCollector
from ansible.module_utils.facts import timeout
from ansible.module_utils.facts.utils import get_file_content, get_mount_size
from ansible.module_utils.facts.sysctl import get_sysctl
class OpenBSDHardware(Hardware):