Simple `pbench-user-benchmark -- sleep 10` leaves a `pidstat` process running for a time afterwards

[portante]

Simple pbench-user-benchmark -- sleep 10 leaves a pidstat process running for a time afterwards.

This problem might be difficult to catch.

The environment was simply created with:

pbench-register-tool-set heavy
pbench-user-benchmark -- sleep 10

At least, we think that was it. It could possibly be related to a containerize environment:

$ cat example.sh
#!/bin/bash
source /opt/pbench-agent/profile
pbench-register-tool-set heavy
pbench-user-benchmark -- sleep 10
$ podman run --rm --name example-with-bash -v ./example.sh:/example.sh:z -v ./var_lib_pbench-agent:/var/lib/pbench-agent:z quay.io/pbench/pbench-agent-all-centos-8:latest /example.sh