task: #1821274 Add back ability to sort on vocabulary weight and name

TaxonomyIndexTid::valueForm() only ordered terms by their own weight/name when a filter spans multiple vocabularies and not by the vocabulary's weight. Since taxonomy_term is a content entity and taxonomy_vocabulary is a config entity, this can't be expressed as a single EntityQuery sort, so the fix keeps the existing weight/name-sorted query and stably sorts the loaded terms by their vocabulary's weight afterward (loading only the vocabularies actually referenced, not all of them). Because the sort is stable, terms within the same vocabulary keep their existing weight/name order.

Added TaxonomyIndexTidFilterTest::testValueFormVocabularyWeightOrdering() covering the ordering.

This issue now depends on #2495191 for Vocabulary::getWeight().

Closes #1821274