fix(field-*): Remove unneeded fieldRegistry.unregister calls

Since FieldAngle, FieldColour and FieldMultilineInput are no longer
in core, there's no longer any need for their corresponding plugins
to unregister the built-in version.

plugins/field-angle/src/field_angle.ts

@@ -668,11 +668,6 @@ export class FieldAngle extends Blockly.FieldNumber {
 
 /** Register the field and any dependencies. */
 export function registerFieldAngle() {
-  // Unregister legacy field_angle that was in core.
-  // TODO(#2194): Delete this once core Blockly no longer defines field_angle.
-  // If field_angle is not defined in core, this generates a console warning.
-  Blockly.fieldRegistry.unregister('field_angle');
-
   Blockly.fieldRegistry.register('field_angle', FieldAngle);
 }
 

plugins/field-colour/src/field_colour.ts

@@ -741,11 +741,6 @@ FieldColour.prototype.DEFAULT_VALUE = '#ffffff';
  * Register the field and any dependencies.
  */
 export function registerFieldColour() {
-  // Unregister legacy field_colour that was in core.
-  // TODO(#2194): Delete this once core Blockly no longer defines field_colour.
-  // If field_colour is not defined in core, this generates a console warning.
-  Blockly.fieldRegistry.unregister('field_colour');
-
   Blockly.fieldRegistry.register('field_colour', FieldColour);
 }
 

plugins/field-multilineinput/src/field_multilineinput.ts

@@ -498,13 +498,6 @@ export class FieldMultilineInput extends Blockly.FieldTextInput {
  * Register the field and any dependencies.
  */
 export function registerFieldMultilineInput() {
-  // Unregister legacy field_multilinetext that was in core.
-  // TODO(2194): Delete this once core Blockly no longer defines
-  // field_multilinetext.
-  // If field_multilinetext is not defined in core,
-  // this generates a console warning.
-  Blockly.fieldRegistry.unregister('field_multilinetext');
-
   Blockly.fieldRegistry.register('field_multilinetext', FieldMultilineInput);
 }