Remove .npmrc from jenkins worker.

This should resolve TE-1835. The jenkins worker no longer
needs the .npmrc file in /home/jenkins due to using
nodeenv for platform builds, and the local copy of .npmrc
which is now stored in the edx-platform repo.

playbooks/roles/jenkins_worker/tasks/system.yml

@@ -51,14 +51,6 @@
   shell: sed -i -r 's/^127.0.0.1\s+.*$/127.0.0.1 localhost preview.localhost/' /etc/hosts
   become: yes
 
-# Npm registry must be pre-loaded or else setting it
-# with the Jenkins user will fail
-# See https://github.com/npm/npm/issues/3565
-- name: Set npm registry
-  template:
-    src=.npmrc.j2 dest={{ jenkins_home }}/.npmrc
-    owner={{ jenkins_user }} group={{ jenkins_group }} mode=0664
-
 # Set up configuration for pip-accel for caching python requirements
 - name: Create directory for pip-accel config file
   file: path={{ jenkins_home }}/.pip-accel state=directory

playbooks/roles/jenkins_worker/templates/.npmrc.j2

-registry={{ COMMON_NPM_MIRROR_URL }}