Remove vue.esm.js from main.bundle.js

The Vue library should not be a part of our main webpack bundle. This was cleaned up in CE with gitlab-ce!11177 but it still seems to be a problem in EE.

see: http://gitlab-org.gitlab.io/gitlab-ee/webpack-report/

The culprit in this case appears to be the inclusion of the projects/settings_service_desk/* component within the main bundle. This needs to be split off into its own bundle, complete with common_vue.

/cc @MadLittleMods