Default access configuration at some (all) places should be BAR rather than BARG

If guest-login is configured and a user changes the access configuration of a course for users into "yes" the default access rule is BARG.
Hence, many users opened their courses unintentional for guests. To manage that, we deactivated the guest-login system wide as a workaround.

It would be better to set BAR by default, even if the guest-login is active, or it should be configurable what the default access is.