pkg/ipc: test only on simple prog
pkg/ipc: test only on simple prog

Don't use random programs for testing.
Sometimes they lead to flakes like:
opendir(./1/file0) failed (errno 13)

xairy/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller