Replace old name with new name

[fjgarlin]

Some of this changes are required after the change of name, otherwise some assets are not found.

Probably use this to update references from Drupal 8 to Drupal 9 too.

Tasks done:

• [x] Replace drupal8ci for drupal9ci where appropriate.
• [x] Replace Drupal 8 for Drupal or Drupal 9 where appropriate.
• [x] Adapted Github actions integration for Drupal 9. See here.
• [x] Removed the dependency on the image with the database to build the actions. Now it tasks mariadb and installs the database before running unit tests.

[juampynr]

Looks good to me so far, @fjgarlin.

[fjgarlin]

Thanks, I think I've got a more simplified version of github actions working now too. Happy for you to review.

[juampynr]

Looks great! Merging.