Revert "vircgroup: cleanup controllers not managed by systemd on error"

Revert "vircgroup: cleanup controllers not managed by systemd on error"

This reverts commit 1602aa28f820ada66f707cef3e536e8572fbda1e.

There is no need to call virCgroupRemove() nor virCgroupFree() if
virCgroupEnableMissingControllers() fails because it will not modify
'group' at all.

The cleanup of directories is done in virCgroupMakeGroup().

Reviewed-by: John Ferlan <jferlan@redhat.com>
Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>