The CI run is failing in the stop command:
```
[ 4841.936906] TEST-71-HOSTNAME.sh[140]: + stop_hostnamed
[ 4841.936906] TEST-71-HOSTNAME.sh[140]: + systemctl stop systemd-hostnamed.service
[ 4845.959747] TEST-71-HOSTNAME.sh[226]: Job for systemd-hostnamed.service canceled.
[ 4846.013286] systemd[1]: TEST-71-HOSTNAME.service: Main process exited, code=exited, status=1/FAILURE
[ 4846.013792] systemd[1]: TEST-71-HOSTNAME.service: Failed with result 'exit-code'.
[ 4846.021821] systemd[1]: Failed to start TEST-71-HOSTNAME.service - TEST-71-HOSTNAME.
```
This happens when we create the stop job, but while we're waiting for
it to finish, something triggers a start of the unit and we lose to competing
start job.
Hopefully fixes#36089.
It will otherwise interpret characters such as '+' as if they
were regex, and break matching.
For example TEST-71-HOSTNAME started failing when
uname -r started including a '+':
FAIL: 'Kernel: Linux 6.12.33+deb13-amd64' not found in:
Static hostname: host
Icon name: computer-vm
Chassis: vm 🖴
Machine ID: e6471c1f95ab49098827498ed816cdf7
Boot ID: 231da987f64d4af59f2076fbb638c611
Virtualization: kvm
Operating System: Debian GNU/Linux 13 (trixie)
Kernel: Linux 6.12.33+deb13-amd64
Architecture: x86-64
Some configuration files that need updates are directly under in /etc. To
update them atomically, we need write access to /etc. For Ubuntu Core this is
an issue as /etc is not writable. Only a selection of subdirectories can be
writable. The general solution is symlinks or bind mounts to writable places.
But for atomic writes in /etc, that does not work. So Ubuntu has had a patch
for that that did not age well.
Instead we would like to introduce some environment variables for alternate
paths.
* SYSTEMD_ETC_HOSTNAME: /etc/hostname
* SYSTEMD_ETC_MACHINE_INFO: /etc/machine-info
* SYSTEMD_ETC_LOCALTIME: /etc/localtime
* SYSTEMD_ETC_LOCALE_CONF: /etc/locale.conf
* SYSTEMD_ETC_VCONSOLE_CONF: /etc/vconsole.conf
* SYSTEMD_ETC_ADJTIME: /etc/adjtime
While it is for now expected that there is a symlink from the standard, we
still try to read them from that alternate path. This is important for
`/etc/localtime`, which is a symlink, so we cannot have an indirect symlink or
bind mount for it.
Since machine-id is typically written only once and not updated. This commit
does not cover it. An initrd can properly create it and bind mount it.
Having these named differently than the test itself mostly creates
unecessary confusion and makes writing logic against the tests harder
so let's rename the testsuite-xx units and scripts to just use the
test name itself.
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Luca Boccassi
Valentin David
Lennart Poettering
Jelle van der Waa
Daan De Meyer