Allows boostrap systemd check to pass if either `systemd` or `systemctl` are found

[dpritchett]

Closes #1019.

Test log

Ubuntu 24.10 box with systemd installed

Correctly identifies the existence of systemctl.

daniel@dp-rb-jupyterhub:~$ cat /proc/version
Linux version 6.11.0-9-generic (buildd@lcy02-amd64-093) (x86_64-linux-gnu-gcc-14 (Ubuntu 14.2.0-4ubuntu2) 14.2.0, GNU ld (GNU Binutils for Ubuntu) 2.43.1) #9-Ubuntu SMP PREEMPT_DYNAMIC Mon Oct 14 13:19:59 UTC 2024
daniel@dp-rb-jupyterhub:~$ ./check_systemd_exists.test.py
INFO:tljh_test:testing systemd binary locator check	python=3.12.7 (main, Feb  4 2025, 14:46:03) [GCC 14.2.0]
INFO:tljh_test:found at least one of systemctl or systemd
INFO:tljh_test:/usr/bin/systemctl
INFO:tljh_test:None

Darwin box with no systemd

Correctly identifies no systemd present.

> uname -a
Darwin johnny-mnemonic 24.4.0 Darwin Kernel Version 24.4.0: Fri Apr 11 18:33:40 PDT 2025; root:xnu-11417.101.15~117/RELEASE_ARM64_T6031 arm64 arm Darwin

the-littlest-jupyterhub on  djp-adjust-systemd-check [?] via 🐍 v3.12.4
> ./check_systemd_exists.test.py
INFO:tljh_test:testing systemd binary locator check	python=3.12.4 (main, Jul 25 2024, 22:11:22) [Clang 18.1.8 ]
ERROR:tljh_test:did not find either systemctl or systemd

Test script used

Full test script for your reference:

#!/usr/bin/env python3

import sys
import shutil
import logging

logger = logging.getLogger('tljh_test')
logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)


logger.info(f'testing systemd binary locator check\tpython={sys.version}')

if not any([shutil.which("systemctl"), shutil.which("systemd")]):
    logger.error("did not find either systemctl or systemd")
else:
    logger.info("found at least one of systemctl or systemd")
    logger.info(shutil.which("systemctl"))
    logger.info(shutil.which("systemd"))

[dpritchett]

Switching to Draft until I sort out the build matrix failures

[manics]

The integration tests are flakey, they've passed after a rerun.