Reasons for creating this PR

See #1838. This implements truncation for the list of terms in other languages on the concept page:

Here is how the result looks like on the YKL/PLC page 32.1 Political systems:

Link to relevant issue(s), if any

• Closes Truncate list of terms in other languages with "show all X values" button #1838
• part of Epic: Concept Page #1484

Description of the changes in this PR

• extend the code in truncate-property-values.js to also handle lists of terms in other languages, which has a somewhat different DOM structure than regular properties
• add a test vocabulary altlabel which contains a concept that has very many English and Finnish language altlabels
• add a Cypress test that tests the truncation functionality with the help of the altlabel vocabulary

Known problems or uncertainties in this PR

1. The limit on the number of items shown is hardcoded at 15, as before. This makes sense for regular properties, but for these terms in other languages, it could perhaps be a bit smaller than that.
2. One of the Cypress tests in global-search-bar.cy.js broke due to the addition of the new altlabel vocabulary. For some reason the testUnknownPropertyOrder vocabulary disappeared from the vocabulary selection menu and was replaced by altlabel. I don't quite understand what happened here; why does the menu only show two vocabularies and not e.g. three? I modified the Cypress test accordingly, but there could be a bug hiding somewhere behind this strange behavior of the vocabulary selection menu.

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)