injection_points: Disable one permutation in isolation test "basic"

injection_points: Disable one permutation in isolation test "basic"

The first permutation done in the test does a wait, a wakeup then a
detach.  It is proving to be unstable in the CI for FreeBSD (Windows and
Linux are stable).  The failure shows that the wait is so slow to finish
after being woken up that the detach has the time to finish before the
wait, messing up with the expected output.

There may be a platform-specific issue going on here, but for now
disable this permutation to make the CI runs more stable.

Discussion: https://postgr.es/m/ZxrnSGdNtQWAxE3_@paquier.xyz