Follow-ups for
ab56a96194d102cb4ec279fc4eb181d16c1251ea.
Fixes the following failure:
```
TEST-87-AUX-UTILS-VM.sh[1196]: + systemd-run --user --wait --pipe -M testuser@.host -- coredumpctl
TEST-87-AUX-UTILS-VM.sh[1840]: Running as unit: run-p1840-i1841.service; invocation ID:
325a026377aa4cffb046c5a63a8906ab
TEST-87-AUX-UTILS-VM.sh[1853]: Hint: You are currently not seeing messages from other users and the system.
TEST-87-AUX-UTILS-VM.sh[1853]: Users in groups 'adm', 'systemd-journal', 'wheel' can see all messages.
TEST-87-AUX-UTILS-VM.sh[1853]: Pass -q to turn off this notice.
TEST-87-AUX-UTILS-VM.sh[1853]: Journal file /var/log/journal/
6835d335b6684b6197bf071ad66f2678/user-4711.journal is truncated, ignoring file.
TEST-87-AUX-UTILS-VM.sh[1853]: No coredumps found.
TEST-87-AUX-UTILS-VM.sh[1840]: Finished with result: exit-code
TEST-87-AUX-UTILS-VM.sh[1840]: Main processes terminated with: code=exited, status=1/FAILURE
TEST-87-AUX-UTILS-VM.sh[1840]: Service runtime: 154ms
TEST-87-AUX-UTILS-VM.sh[1840]: CPU time consumed: 78ms
TEST-87-AUX-UTILS-VM.sh[1840]: Memory peak: 21.9M (swap: 0B)
```
# Wait a bit for the coredumps to get processed
timeout 30 bash -c "while [[ \$(coredumpctl list -q --no-legend $CORE_TEST_UNPRIV_BIN | wc -l) -lt 4 ]]; do sleep 1; done"
+# Sync and rotate journal again to make the coredump stored in an archived journal.
+journalctl --sync
+journalctl --rotate
+
# root should see coredumps from both binaries
coredumpctl info "$CORE_TEST_UNPRIV_BIN"
coredumpctl info "${CORE_TEST_UNPRIV_BIN##*/}"