Verify downstream pipeline eligibility only once when multiple generated maven artifacts trigger a pipeline.

When enabling an eligibility check is skipped and logging org.jenkinsci.plugins.pipeline.maven.listeners.DownstreamPipelineTriggerRunListener=FINEST is enabled,
then the following style of log message will be displayed in build logs:

[withMaven - DownstreamPipelineTriggerRunListener] Skip eligibility check of pipeline dependency-graph/my-downstream-of-a-multi-jar-project/master for artifact com.example.multi-jar:jar-2:jar:0.0.1-SNAPSHOT(0.0.1-20180903.201513-17), eligibility already confirmed