Adjust the detection of the running pipelines to the changed log format of Logstash > 8.11.x
Update README with instructions on how to run the integration tests
These Changes have been successfully tested with Logstash 7.x (namely 7.13.0), Logstash 8.x (namely 8.0.2, 8.9.2, 8.11.4, 8.12.1, 8.13.4) but it might also work with other versions.
Logstash Filter Verifier does not work with Logstash 8.10.x due to a brocken JSON serializer used for logging (see https://github.com/elastic/logstash/pull/15564).
This PR restores compatibility with Logstash 8:
These Changes have been successfully tested with Logstash 7.x (namely 7.13.0), Logstash 8.x (namely 8.0.2, 8.9.2, 8.11.4, 8.12.1, 8.13.4) but it might also work with other versions. Logstash Filter Verifier does not work with Logstash 8.10.x due to a brocken JSON serializer used for logging (see https://github.com/elastic/logstash/pull/15564).