AJAX is broken on the add condition form

Problem/Motivation

🐛 AJAX is broken on the add condition form Needs review must be merged first. This issue is about the same, but in Page Manager module. It overrides the \Drupal\ctools\Form\ManageConditions::add() method and causes AJAX to be broken on condition forms.

Proposed resolution

• Delete all overrides of \Drupal\ctools\Form\ManageConditions::add() as the approach with sub-request makes them unnecessary.
• Delete implementations of \Drupal\ctools\Form\ManageConditions::getConditionClass() which is deleted in 🐛 AJAX is broken on the add condition form Needs review .

Remaining tasks

• Once Ctools module version with 🐛 AJAX is broken on the add condition form Needs review is released, add this version to the list of dependencies.

User interface changes

No.

API changes

See proposed resolution.

Data model changes

No.