[dbapi] fix connect backwards compat harder
Passing None as group and host should result in
"pyro:///cubicweb.appid", not "pyro://None/None.appid". Followup for
2091d275fe5c. Closes #2882666.
option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')