Don't require a global backened secret when allowall is not set

[SystemKeeper]

☑️ Resolves

• Fix Global secret for recording server backend should not be needed #9580

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not required
• 📘 API documentation in docs/ has been updated or is not required
• 📗 User documentation in https://github.com/nextcloud/documentation/tree/master/user_manual/talk has been updated or is not required
• 🔖 Capability is added or not needed

[danxuliu]

I would prefer something like if self._configParser.get('backend', 'allowall', fallback=None) == 'true' instead for consistency with other boolean options (as otherwise this would accept 1/0, yes/no... while the other would only accept true/false (ok, strictly speaking, true /anything else :-P ).

Alternatively _getBackendValue could be extended with _getBackendBooleanValue and _getBackendIntValue... but checking against 'true' is easier ;-)

[SystemKeeper]

I would prefer something like if self._configParser.get('backend', 'allowall', fallback=None) == 'true'

Sure - fine by me :-) PR updated.

[danxuliu]

Tested and works 👍