jenkins: only update sonarqube when on develop branch

Jenkinsfile.groovy

@@ -32,12 +32,17 @@ pipeline {
                     sh "${mvn} checkstyle:checkstyle"
                     sh "${mvn} pmd:pmd"
                     pmd canComputeNew: false, defaultEncoding: '', healthy: '', pattern: '', unHealthy: ''
+                }
+            }
+        }
+        stage('SonarQube (develop only)') {
+            when { expression { env.GIT_BRANCH == 'develop' } }
+            steps {
                 withSonarQubeEnv('sonarqube') {
                     sh "${mvn} org.sonarsource.scanner.maven:sonar-maven-plugin:3.4.0.905:sonar"
                 }
             }
         }
-        }
         stage('Build Java Next') {
             when { expression { true == false } }
             steps {