Context
Recently, the Node-specific CI jobs were upgrade from Node 14 to Node 16 (see T314470), this caused Wikibase CI to fail for tainted references (see T330380), and a band-aid solution was applied (see Fix tainted-ref CI after Node v16 upgrade).
This is complicated by the fact that the jobs running the browser tests still are required to run Node 14, because the Selenium browser tests are written in the synchronous style, which no longer works with Node 16. There is one approach for refactoring those tests, see T300811, and one for reconsidering our stack for browser tests in general, see T180228 (given that we also still have ruby browser tests...).

Acceptance Criteria

• the band-aid script added in extensions/Wikibase/+/891259 has been removed and everything works natively in Node16
• double-checked that the test:distnodiff does work as expected (the above patch does not include a change to dist/, which is unintuitive)