Create Node.js 10 job for 'npm run {script}' (and switch VE)

The npm6 version of this job template was only used by VisualEditor,
which this commit replaces and removes from templates:

• {name}-npm6-node-6-docker
• {name}-npm6-browser-node-6-docker
• {name}-npm6-run-{script}-node-6-docker

VisualEditor also had an npm(3) version of this job still,
which was already used, and thus also removed from jobs:

• 'visualeditor-npm-browser-node-6-docker'
• 'visualeditor-npm-run-{script}-node-6-docker'

Bug: T211784
Change-Id: I5eaa15750af20ceb8674540bdcd65c525d90972b