rsyslog service fails to start when using SSL/TLS configuration using a passphrase protected key

Issue

• When starting the rsyslog service after configuring SSL/TLS using a passphrase protected key, the service fails to start with similar errors:

  Mar 09 16:41:21 server.example.com systemd[1]: Starting System Logging Service...
  Mar 09 16:41:21 server.example.com rsyslogd[6659]:  [origin software="rsyslogd" swVersion="8.24.0-57.el7_9.1" x-pid="6659" x-info="http://www.rsyslog.com"] start
  Mar 09 16:41:21 server.example.com rsyslogd[6659]: unexpected GnuTLS error -24 in nsd_gtls.c:589: Decryption has failed.  [v8.24.0-57.el7_9.1 try http://www.rsyslog.com/e/2078 ]
  Mar 09 16:41:21 server.example.com rsyslogd[6659]: error adding our certificate. GnuTLS error -24, message: 'Decryption has failed.', key: '/etc/pki/tls/private/key.key', cert: '/etc/pki/tls/certs/cert.crt' [v8.24.0-57.el7_9.1 try http://www.rsyslog.com/e/2078 ]
  Mar 09 16:41:21 server.example.com rsyslogd[6659]: Could not create tcp listener, ignoring port 6514 bind-address (null). [v8.24.0-57.el7_9.1 try http://www.rsyslog.com/e/2078 ]
  Mar 09 16:41:21 server.example.com systemd[1]: Started System Logging Service.