Breaking: #96263 - Remove jQuery promise support for AJAX requests

Description

With forge#89738, a polyfill for jQuery promises was introduced to ease the migration of $.ajax() to our AJAX request API.

The polyfilled methods done() and fail() are now removed.

Impact

Relying on the existence of the polyfill will trigger JavaScript errors.

Affected Installations

All extensions using the polyfilled methods are affected.

Migration

For success handling, replace done() with then().

Example:

// Polyfill
new AjaxRequest('/foobar/baz').get().done(function(response) {
  // do stuff
});

// Native
new AjaxRequest('/foobar/baz').get().then(async function(response) {
  // do stuff
});

For error handling, replace fail() with catch().

Example:

// Polyfill
new AjaxRequest('/foobar/baz').get().fail(function() {
  // oh noes
});

// Native
new AjaxRequest('/foobar/baz').get().catch(function() {
  // oh noes
});