[CI]: Syslog is flaky: TestSyslogNetwork TestSyslogFacilities

### Description

This is from #4140 and is one of the failing tests hidden behind retries.

This is not the only log related flaky test.
Either there is some (expected?) delay in logs propagation and we should have a better logic in tests to account for that, or there is an underlying issue with logs generally.

### Steps to reproduce the issue

_No response_

### Describe the results you received and expected

```
=== RUN TestSyslogNetwork/unixgram_user_rfc5424
container_run_log_driver_syslog_test.go:109: s.Info() = '""', didn't match '"<14>%d %s %s nerdctl-testsyslognetwork-unixgram_user_rfc5424_syslog_driver %d nerdctl-testsyslognetwork-unixgram_user_rfc5424_syslog_driver - hello, nerdctl-testsyslognetwork-unixgram_user_rfc5424_syslog_driver\n"' (0 unexpected EOF)
--- FAIL: TestSyslogNetwork/unixgram_user_rfc5424 (0.55s)
FAIL cmd/nerdctl/container.TestSyslogNetwork/unixgram_user_rfc5424 (0.55s)
=== RUN TestSyslogNetwork/unixgram_1_rfc5424
container_run_log_driver_syslog_test.go:109: s.Info() = '""', didn't match '"<14>%d %s %s nerdctl-testsyslognetwork-unixgram_1_rfc5424_syslog_driver %d nerdctl-testsyslognetwork-unixgram_1_rfc5424_syslog_driver - hello, nerdctl-testsyslognetwork-unixgram_1_rfc5424_syslog_driver\n"' (0 unexpected EOF)
--- FAIL: TestSyslogNetwork/unixgram_1_rfc5424 (0.80s)
FAIL cmd/nerdctl/container.TestSyslogNetwork/unixgram_1_rfc5424 (0.80s)
=== RUN TestSyslogNetwork
--- FAIL: TestSyslogNetwork (5.65s)
```

### What version of nerdctl are you using?

main

### Are you using a variant of nerdctl? (e.g., Rancher Desktop)

None

### Host information

_No response_