Use artifact caching proxy for Jenkins Core builds (#7649)

* Use artifact caching proxy for Jenkins Core builds

* pipeline library PR merged

* restore empty line

Jenkinsfile

@@ -152,7 +152,9 @@ builds.ath = {
       // Just to be safe
       deleteDir()
       checkout scm
-      sh 'bash ath.sh'
+      infra.withArtifactCachingProxy {
+        sh 'bash ath.sh'
+      }
       junit testResults: 'target/ath-reports/TEST-*.xml', testDataPublishers: [[$class: 'AttachmentPublisher']]
     }
   }

ath.sh

@@ -8,9 +8,12 @@ cd "$(dirname "$0")"
 # https://github.com/jenkinsci/acceptance-test-harness/releases
 export ATH_VERSION=5497.vca_4a_876045ce
 
-# TODO use Artifactory proxy?
+MVN='mvn -B -ntp -Pquick-build -am -pl war package'
+if [[ -n ${MAVEN_SETTINGS-} ]]; then
+	MVN="${MVN} -s ${MAVEN_SETTINGS}"
+fi
 
-[[ -f war/target/jenkins.war ]] || mvn -B -ntp -Pquick-build -am -pl war package
+[[ -f war/target/jenkins.war ]] || $MVN
 
 mkdir -p target/ath-reports
 chmod a+rwx target/ath-reports