test_js_license_set is bogus and unreliable

[mattpap]

After changes to bokehjs' build setup, package.json files, etc., license-checker returns bogus results in production mode, which the test uses:

~/repo/bokeh/bokehjs$ npx license-checker --summary --production
└─ BSD-3-Clause: 1

Otherwise, it returns a lot of licenses that aren't present in bokehjs' bundles:

~/repo/bokeh/bokehjs$ npx license-checker --summary
├─ MIT: 265
├─ ISC: 28
├─ BSD-3-Clause: 15
├─ BSD-2-Clause: 12
├─ Apache-2.0: 11
├─ UNLICENSED: 5
├─ 0BSD: 2
├─ (Unlicense OR Apache-2.0): 1
├─ Python-2.0: 1
├─ (MIT OR Apache-2.0): 1
├─ (MIT OR CC0-1.0): 1
└─ MIT*: 1

Additionally, it reports different licenses in CI and locally.

I disabled this test in PR #12219, to allow to merge this PR. We will have to figure out a more robust way of checking licenses. Also, minified bundles are stripped of licences, whereas unminified bundles contain them.

[bryevdv]

Also, minified bundles are stripped of licences.

This should not be done. People have loudly complained about it in the past. Most licenses are clear about being distributed with published derivative works.

[bryevdv]

I was going to move this out of 3.1 milestone but we need to first confirm that bundles do not strip out licenses.

[mattpap]

I visually confirmed that bokeh*.min.js bundles contain third-party licenses, though it looks like not all of them. It may be due to the minifier not being able to recognize comments with license information (it's customary to use /*! style comments for comments that are expected to be preserved, but not everyone uses those), or such information is not provided in source files.