Issue #3468280 by catch, bbrala: Speed up JSON:API ResourceTestBase

core/modules/jsonapi/tests/src/Functional/CommentTest.php

core/modules/jsonapi/tests/src/Functional/FileTest.php

core/modules/jsonapi/tests/src/Functional/FileUploadTest.php

core/modules/jsonapi/tests/src/Functional/MediaTest.php

core/modules/jsonapi/tests/src/Functional/MessageTest.php

...modules/jsonapi/tests/src/Functional/ResourceTestBase.php

core/modules/jsonapi/tests/src/Functional/UserTest.php