Issue #2712505 by StryKaizer: Clean up facet add form

.../Plugin/facets/facet_source/CoreNodeSearchFacetSource.php

core_search_facets/src/Tests/IntegrationTest.php

facets.libraries.yml

js/edit-facet.js

src/Form/FacetDisplayForm.php

src/Form/FacetForm.php

src/Plugin/facets/facet_source/SearchApiBaseFacetSource.php

src/Tests/ExampleContentTrait.php

src/Tests/IntegrationTest.php

src/Tests/UrlIntegrationTest.php

src/Tests/WidgetIntegrationTest.php