oslo doesn't react correctly to missing/non-accessible config files

[Nicolas Formichella]

Installing `placement` fails

- Entered the correct database URL
- sudo -u placement placement-manage db sync succeeds
- `placement-status --debug upgrade check` fails with :

Traceback (most recent call last):
  File "/usr/bin/placement-status", line 10, in <module>
    sys.exit(main())
  File "/usr/lib/python3/dist-packages/placement/cmd/status.py", line 140, in main
    config(args=sys.argv[1:], project='placement')
  File "/usr/lib/python3/dist-packages/oslo_config/cfg.py", line 2163, in __call__
    self._check_required_opts()
  File "/usr/lib/python3/dist-packages/oslo_config/cfg.py", line 2906, in _check_required_opts
    raise RequiredOptError(opt.name, group)
oslo_config.cfg.RequiredOptError: value required for option connection in group [placement_database]

----

OS : Ubuntu 22.04
Openstack Release : Bobcat

[Nicolas Formichella (signed)]

Duplicate of https://storyboard.openstack.org/#!/story/2008969

[Nicolas Formichella (signed)]

The issue seems to actually lie in oslo.config

The stock (before the groupadd of the above link) config is not accessible by non-root

```
-rw-r----- 1 root placement 26376 Mar 12 09:46 placement.conf
```

The config doesn't exist for oslo.config

```
--- a/oslo_config/cfg.py
+++ b/oslo_config/cfg.py
@@ -2028,7 +2028,7 @@ class ConfigOpts(abc.Mapping):
                                               '--version',
                                               action='version',
                                               version=version)
-
+ print(locals())
         return prog, default_config_files, default_config_dirs
```

```
{'self': <oslo_config.cfg.ConfigOpts object at 0x7f813ec76da0>, 'project': 'placement', 'prog': 'placement-status', 'version': None, 'usage': None, 'description': None, 'epilog': None, 'default_config_files': [], 'default_config_dirs': []}
```

```
--- a/oslo_config/cfg.py
+++ b/oslo_config/cfg.py
@@ -2163,6 +2163,7 @@ class ConfigOpts(abc.Mapping):

         self._namespace = self._parse_cli_opts(args if args is not None
                                                else sys.argv[1:])
+ print(vars(self._namespace))
         if self._namespace._files_not_found:
             raise ConfigFilesNotFoundError(self._namespace._files_not_found)
         if self._namespace._files_permission_denied:
```

{'_conf': <oslo_config.cfg.ConfigOpts object at 0x7ff59557eda0>, '_parsed': [], '_normalized': [], '_emitted_deprecations': set(), '_files_not_found': [], '_files_permission_denied': [], '_config_dirs': [], '_sections_to_file': {}, 'command': 'upgrade', 'config_dir': None, 'config_file': None, 'debug': None, 'log_config_append': None, 'log_date_format': None, 'log_dir': None, 'log_file': None, 'use_journal': None, 'use_json': None, 'use_syslog': None, 'watch_log_file': None, 'syslog_log_facility': None, 'check': 'check', 'json': False, 'action_fn': <bound method UpgradeCommands.check of <placement.cmd.status.Checks object at 0x7ff592ecaf50>>}

It fills neither `_files_not_found` nor `_files_permission_denied`