Prior work:

• T267891: Create Debian packages for Node.js 14 upgrade
• T267888: Create WMF CI image for Node.js 14
• T267889: Update Fresh from Node.js 10 LTS to Node.js 14 LTS

In the previous release, we switched the default from Node 10 to Node 12, and added Node 14 as an option.

For the next release, I suggest we switch the default from Node 12 to Node 14, and keep Node 12 as an option.

This is motivated by two things:

1. The Jenkins jobs for most projects in WMF CI has moved from Node 12 to Node 14, and fresh-node aims to match the reality in WMF CI. T267890
2. Node 12 LTS is officialy end-of-life as of last week, 2022-04-30 (release schedule, official page).