jenkins: fix npm build, removing docker -u

npm writes to ~/.npm, and reads ~/.npmrc. But user 910 does
not exist in container, so has no home directory. Therefore
npm fails. Reverting `-u` for now.
diff --git a/Jenkinsfile b/Jenkinsfile
index f37b75f..c41da46 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -38,7 +38,7 @@
             }
 
             stage('Run tests') {
-                environmentDockerImage.inside('-i --rm --name brooklyn-${DOCKER_TAG} -u 910:910 --mount type=bind,source="${HOME}/.m2/settings.xml",target=/var/maven/.m2/settings.xml,readonly -v ${WORKSPACE}:/usr/build -w /usr/build') {
+                environmentDockerImage.inside('-i --rm --name brooklyn-${DOCKER_TAG} --mount type=bind,source="${HOME}/.m2/settings.xml",target=/var/maven/.m2/settings.xml,readonly -v ${WORKSPACE}:/usr/build -w /usr/build') {
                     sh 'mvn clean install -Duser.home=/var/maven -Duser.name=jenkins'
                 }
             }
@@ -46,7 +46,7 @@
             // Conditional stage to deploy artifacts, when not building a PR
             if (env.CHANGE_ID == null) {
                 stage('Deploy artifacts') {
-                    environmentDockerImage.inside('-i --rm --name brooklyn-${DOCKER_TAG} -u 910:910 --mount type=bind,source="${HOME}/.m2/settings.xml",target=/var/maven/.m2/settings.xml,readonly -v ${WORKSPACE}:/usr/build -w /usr/build') {
+                    environmentDockerImage.inside('-i --rm --name brooklyn-${DOCKER_TAG} --mount type=bind,source="${HOME}/.m2/settings.xml",target=/var/maven/.m2/settings.xml,readonly -v ${WORKSPACE}:/usr/build -w /usr/build') {
                         sh 'mvn deploy -DskipTests -Duser.home=/var/maven -Duser.name=jenkins'
                     }
                 }