TestHello leaks runj-entrypoint processes

[samuelkarp]

$ ps aux | grep runj-entrypoint
sam   75911   0.0  0.1   12796  2312  0  S+   09:50        0:00.00 grep runj-entrypoint
root  10036   0.0  0.0  728272   516  1- I    10Dec23      0:00.79 runj-entrypoint integ-test-hooks /var/lib/runj/jails/integ-test-hooks/exec.fifo /integ-inside -test.
root   4251   0.0  0.0  728016   456  3- I     8Dec23      0:00.84 runj-entrypoint integ-test-hooks /var/lib/runj/jails/integ-test-hooks/exec.fifo /integ-inside -test.
root   4671   0.0  0.0  728272   460  4- I     8Dec23      0:00.84 runj-entrypoint integ-test-hooks /var/lib/runj/jails/integ-test-hooks/exec.fifo /integ-inside -test.
root   4984   0.0  0.0  728272   460  5- I     8Dec23      0:00.86 runj-entrypoint integ-test-hooks /var/lib/runj/jails/integ-test-hooks/exec.fifo /integ-inside -test.
root  33454   0.0  0.0  728272   460  6- I    20Dec23      0:00.41 runj-entrypoint integ-test-hooks /var/lib/runj/jails/integ-test-hooks/exec.fifo /integ-inside -test.
root  55763   0.0  0.1  728272  4308  7- I    21Dec23      0:00.38 runj-entrypoint integ-test-hooks /var/lib/runj/jails/integ-test-hooks/exec.fifo /integ-inside -test.

[petderek]

I can take a stab at this