Move trivially compatible tests to the unit tests suite

This changeset resumes work on T89432 and related tickets
by porting an initial set of tests to the new unit test suite
separated out in I69b92db3e70093570e05cc0a64c7780a278b321a.
The tests were only ported if they worked immediately without
requiring any changes other than changing the test case class
to MediaWikiUnitTestCase and moving the test to the new suite.
If a test failed for any reason (even trivial misconfiguration),
it was NOT ported.

With this change, the unit tests suite now consits of a total
of 455 tests. As before, you can run these tests via the following
command:
$ composer phpunit:unit

Bug: T84948
Bug: T89432
Bug: T87781
Change-Id: Ibb8175981092d7f41864e641cc3c118af70a5c76