MAAS' nginx attempts to log in default locations for snap, gets permission denied

[Christian Grabowski]

When running MAAS in a snap, nginx attempts to log in its default locations (/var/log/nginx/access.log, /var/log/nginx/error.log) these locations are read-only in the snap and nginx errors with permission denied.

nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)
nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)
nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)
nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)

This does not prevent nginx from functioning, but does prevent debugging issues.