ubuntu-2404 flake, journalctl --sync fails in TestHistoryMetrics.testEvents

[jelly]

Failed to connect to /run/systemd/journal/io.systemd.journal: Connection refused
Traceback (most recent call last):
  File "/work/make-checkout-workdir/test/common/testlib.py", line 2055, in tearDown
    self.check_journal_messages()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/work/make-checkout-workdir/test/common/testlib.py", line 2280, in check_journal_messages
    messages = machine.journal_messages(matches, 6, cursor=cursor)
  File "/work/make-checkout-workdir/bots/machine/machine_core/machine.py", line 179, in journal_messages
    self.execute("sleep 1; journalctl --sync")
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/work/make-checkout-workdir/bots/machine/machine_core/ssh_connection.py", line 337, in execute
    res = subprocess.run(command_line,
                         input=input.encode("UTF-8") if input else b'',
                         stdout=stdout, check=check)
  File "/usr/lib64/python3.14/subprocess.py", line 577, in run
    raise CalledProcessError(retcode, process.args,
                             output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '('env', '-u', 'LANGUAGE', 'LC_ALL=C', 'ssh', '-F', 'none', '-o', 'BatchMode=yes', '-o', 'IdentitiesOnly=yes', '-o', 'PKCS11Provider=none', '-o', 'StrictHostKeyChecking=no', '-o', 'UserKnownHostsFile=/dev/null', '-oHostname=127.0.0.2', '-oLogLevel=ERROR', '-oPort=2701', '-oUser=root', '-oControlPath=/tmp/.cockpit-test-resources/ssh-%C-50687', 'vm', 'set -e;', 'sleep 1; journalctl --sync')' returned non-zero exit status 1.

This specific test somehow crashes? Or makes journald busy so we can't --sync. Anyway requires investigation.