Bump jenkins core to LTS 1.609.3. Removed maven-plugin dependency. Added powermockito.
Bump jenkins core to LTS 1.609.3. Removed maven-plugin dependency. Added powermockito.

escoem/jira-plugin,deki/jira-plugin,deki/jira-plugin,warden/jira-plugin,kuldazbraslav/jira-plugin,kuldazbraslav/jira-plugin,escoem/jira-plugin,warden/jira-plugin