[migration] don't crash when deleting a non-existing rtype
When asked to delete a relation type, instead of checking if it was
computed or not, just delete both the CWRType and CWComputedRType.
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')