Align default button styles more closely on Drupal core

stefan.korn → changed the visibility of the branch 3474980-align-default-button to hidden.

@stefan.korn
can you please provide screenshots before/after of the MR, and Claro example you've described in the issue.
This will make it easier and faster to confirm the issue and review solution.

thank you!

@jannakha: Please see screenshots

Claro:

Bootstrap5 without this MR (notice both Save and Preview are primary):

Bootstrap5 with this MR (Preview now Secondary):

This is good to go.

This btn-primary class being added to everything comes from #3249388: Styling update → - it seems hard to see why it would have been intentional.

The field-add-more-submit changes came from #3190309: Replace v4 with v5 library → and also seem unintentional and makes sense to remove.

Marked ✨ Primary buttons are the same color as other buttons Active as a duplicate of this as it takes exactly the same approach, but is just missing the "Add more" changes that are included here.