tox-bootstrapd can use around 600 TCP sockets during TCP server's normal
functioning. Many systems default to having a soft limit of 1024 open file
descriptors, which we are close to reaching, so it was suggested we bump that
limit to a higher number. iphy suggested increasing it to 32768.
@arthurtiteica has pointed out that systemd has more suitable facilities for
creating a temporary directory for a PID file rather than calling ExecStartPre,
which requires an absolute path to coreutils executables we used for creating a
directory and changing its owner, paths of which are are not universal across
distributions. Systemd can take care of it for us without need to provide
absolute paths, which is what we use here.
