fix(material/button-toggle): remove deprecated factory functions

Removes factory functions that we had marked as deprecated for v21. These functions aren't necessary since we switched to standalone.

BREAKING CHANGE:
* `MAT_BUTTON_TOGGLE_GROUP_DEFAULT_OPTIONS_FACTORY` has been removed.

Author: crisbeto

goldens/material/button-toggle/index.api.md

@@ -23,9 +23,6 @@ export const MAT_BUTTON_TOGGLE_DEFAULT_OPTIONS: InjectionToken<MatButtonToggleDe
 // @public
 export const MAT_BUTTON_TOGGLE_GROUP: InjectionToken<MatButtonToggleGroup>;
 
-// @public @deprecated
-export function MAT_BUTTON_TOGGLE_GROUP_DEFAULT_OPTIONS_FACTORY(): MatButtonToggleDefaultOptions;
-
 // @public
 export const MAT_BUTTON_TOGGLE_GROUP_VALUE_ACCESSOR: any;
 

src/material/button-toggle/button-toggle.ts

@@ -82,23 +82,14 @@ export const MAT_BUTTON_TOGGLE_DEFAULT_OPTIONS = new InjectionToken<MatButtonTog
   'MAT_BUTTON_TOGGLE_DEFAULT_OPTIONS',
   {
     providedIn: 'root',
-    factory: MAT_BUTTON_TOGGLE_GROUP_DEFAULT_OPTIONS_FACTORY,
+    factory: () => ({
+      hideSingleSelectionIndicator: false,
+      hideMultipleSelectionIndicator: false,
+      disabledInteractive: false,
+    }),
   },
 );
 
-/**
- * @docs-private
- * @deprecated No longer used, will be removed.
- * @breaking-change 21.0.0
- */
-export function MAT_BUTTON_TOGGLE_GROUP_DEFAULT_OPTIONS_FACTORY(): MatButtonToggleDefaultOptions {
-  return {
-    hideSingleSelectionIndicator: false,
-    hideMultipleSelectionIndicator: false,
-    disabledInteractive: false,
-  };
-}
-
 /**
  * Injection token that can be used to reference instances of `MatButtonToggleGroup`.
  * It serves as alternative token to the actual `MatButtonToggleGroup` class which