sysutils/logstash8: Update 8.19.13 => 8.19.15

Release Notes:
https://www.elastic.co/guide/en/logstash/8.19/logstash-8-19-14.html
https://www.elastic.co/guide/en/logstash/8.19/logstash-8-19-15.html

PR: 294181
Approved by: elastic (maintainer, timeout 3 weeks)
Sponsored by: UNIS Labs