Use proper user in node container and add cleanup

Change-Id: Ibaeb2c9daf4243deb3908d9fdb1d4f120e59cbb5
Related-task: #PROD-25044 (PROD:25044)
diff --git a/test-operations-ui.groovy b/test-operations-ui.groovy
index f813524..b6c8b27 100644
--- a/test-operations-ui.groovy
+++ b/test-operations-ui.groovy
@@ -52,9 +52,8 @@
 
             if (checkouted) {
                 stage("test") {
-                    img.inside("-v ${env.WORKSPACE}/:/operations-ui/") {
+                    img.inside("-u root:root -v ${env.WORKSPACE}/:/operations-ui/ -e npm_config_cache=/operations-ui/.npm -e CI=true") {
                         sh('''#!/bin/bash -xe
-                          export CI=true
                           cd /operations-ui
                           npm install
                           npm test
@@ -70,6 +69,11 @@
             if (fileExists(testReportFile)) {
                 archiveArtifacts artifacts: testReportFile
             }
+            stage("Cleanup"){
+                img.inside("-u root:root -v ${env.WORKSPACE}/:/operations-ui/") {
+                    sh("rm -rf /operations-ui/*")
+                }
+            }
         }
     }
 }