block: Fix Transaction leak in bdrv_reopen_multiple()

Like other error paths, this one needs to call tran_finalize() and clean
up the BlockReopenQueue, too.

Fixes: CID 1452772
Fixes: 72373e40
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210503110555.24001-3-kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>