qcow2: Fix open/create to open images with no_co_wrapper

.bdrv_co_create implementations run in a coroutine, as does
qcow2_do_open(). Therefore they are not allowed to open images directly.
Fix the calls to use the corresponding no_co_wrappers instead.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230126172432.436111-7-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>