Comment 1 for bug 2038607

When backup_protocol_access_mapping I see
```
2023-10-06 06:03:00.001 76696 DEBUG manila.service [-] backup_protocol_access_mapping = {'ip': ['nfs']} log_opt_values /usr/lib/python3.9/site-packages/oslo_config/cfg.py:2602
```
in manila data log when manila-data starts.

Then if I add
```
[DEFAULT]
backup_protocol_access_mapping=ip:nfs
```
to manila.conf then the start up log shows
```
2023-10-06 10:38:22.143 71627 DEBUG manila.service [-] backup_protocol_access_mapping = {'ip': 'nfs'} log_opt_values /usr/lib/python3.9/site-packages/oslo_config/cfg.py:2602
```

If I try the format described in the generated config file
```
[DEFAULT]
backup_protocol_access_mapping=ip:['nfs']
```
then this results in
```
2023-10-06 13:53:37.513 71612 DEBUG manila.service [-] backup_protocol_access_mapping = {'ip': "['nfs']"} log_opt_values /usr/lib/python3.9/site-packages/oslo_config/cfg.py:2602
```