[TASK] Remove unused FormEngine.legacyFieldChangedCb()

The method `FormEngine.legacyFieldChangedCb()` was used back in the days
by legacy FormEngine which passed a callback function via the PHP
property `TBE_EDITOR_fieldChanged_func`. Later on, the configuration
`TYPO3.settings.FormEngine.legacyFieldChangedCb` was used.

Neither TYPO3 core, nor any extension available in TER use this relict.
It is therefore safe to assume we can remove this method without being a
breaking change.

Resolves: #106278
Releases: main, 13.4
Change-Id: I6c47998edf5da042f0952c9dd3f28a2b879641af
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/88407
Reviewed-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>

Author: andreaskienast

Build/Sources/TypeScript/backend/form-engine.ts

@@ -50,7 +50,6 @@ type FormEngineType = {
   formName: string,
   formElement: HTMLFormElement,
   openedPopupWindow: Window | null,
-  legacyFieldChangedCb: () => void,
   browserUrl: string,
   doSaveFieldName: string,
 };
@@ -152,11 +151,6 @@ export default (function() {
     formName: TYPO3.settings.FormEngine.formName,
     formElement: undefined,
     openedPopupWindow: null,
-    legacyFieldChangedCb: function() {
-      if ($.isFunction(TYPO3.settings.FormEngine.legacyFieldChangedCb)) {
-        TYPO3.settings.FormEngine.legacyFieldChangedCb();
-      }
-    },
     browserUrl: '',
     doSaveFieldName: ''
   };
@@ -320,8 +314,6 @@ export default (function() {
         // set the hidden field
         FormEngine.updateHiddenFieldValueFromSelect(fieldEl, originalFieldEl);
 
-        // execute the phpcode from $FormEngine->TBE_EDITOR_fieldChanged_func
-        FormEngine.legacyFieldChangedCb();
         FormEngine.Validation.markFieldAsChanged(originalFieldEl);
         FormEngine.Validation.validateField(fieldEl);
         FormEngine.Validation.validateField(availableFieldEl);

Build/Sources/TypeScript/backend/form-engine/element/abstract-sortable-select-items.ts

@@ -138,7 +138,6 @@ export abstract class AbstractSortableSelectItems {
       }
 
       FormEngine.updateHiddenFieldValueFromSelect(fieldElement, relatedField);
-      FormEngine.legacyFieldChangedCb();
       FormEngineValidation.markFieldAsChanged(relatedAvailableValuesField);
       FormEngineValidation.validateField(relatedAvailableValuesField);
     });
@@ -178,7 +177,6 @@ export abstract class AbstractSortableSelectItems {
       }
       if (e.defaultPrevented) {
         FormEngine.updateHiddenFieldValueFromSelect(fieldElement, relatedField);
-        FormEngine.legacyFieldChangedCb();
         FormEngineValidation.markFieldAsChanged(relatedAvailableValuesField);
         FormEngineValidation.validateField(relatedAvailableValuesField);
       }

Build/types/TYPO3/index.d.ts

@@ -53,7 +53,6 @@ declare namespace TYPO3 {
       export const formName: string;
 
       export const doSaveFieldName: string;
-      export const legacyFieldChangedCb: () => void;
     }
     export namespace FormEngineInline {
       export const config: {