Resolve #3559954 "Fix phpunit tests"

https://www.drupal.org/project/block_class/issues/3559954

Automated tests: Fix tests compatibility with Drupal core 11.3.x (next minor) and support for Drupal core 9.5.x (deprecated major).
Brought back code from function providerTest before it was changed in previous commit to maintain support for D9, see: 8bd289e5.