vm/qemu: fix spurious failure during VM creation
vm/qemu: fix spurious failure during VM creation

When we recover from a transient failure, we want to cleanup
everything except for the workdir, because we will use it again
during next VM creation attempt.
Currently the next attempt always fails.

dotweiba/syzkaller,dotweiba/syzkaller,xairy/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,sploving/syzkaller,hyz0906/syzkaller,hyz0906/syzkaller,xairy/syzkaller,dotweiba/syzkaller,hyz0906/syzkaller,google/syzkaller,zoulasc/syzkaller,google/syzkaller,google/syzkaller,hyz0906/syzkaller,hyz0906/syzkaller,zoulasc/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,sploving/syzkaller,dotweiba/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,zoulasc/syzkaller,sploving/syzkaller,sploving/syzkaller,zoulasc/syzkaller