enable the logging_syslogd_append_public_content boolean
    
    The test reproduces scenarios described in 2 different bugs. One of
    them is BZ#1823672. If this scenario should succeed, a newly introduced
    boolean called logging_syslogd_append_public_content needs to be enabled.
    The scenario also requires that the target log file exists before
    the rsyslogd process tries to append to it.