refactor(common): remove remaining code for NgSwitch equality patch (#56806)

This change is the final cleanup after removing NgSwitch's equality patch
that was used in G3 to allow == matching for a certain period of time. This
code is no longer needed as both the external ecosystem and G3 are using
=== equality for matching NgSwitch cases.

PR Close #56806

packages/common/src/directives/ng_switch.ts

@@ -14,7 +14,6 @@ import {
   Optional,
   TemplateRef,
   ViewContainerRef,
-  ɵformatRuntimeError as formatRuntimeError,
   ɵRuntimeError as RuntimeError,
 } from '@angular/core';
 

packages/common/src/directives/ng_switch_equality.ts

@@ -1,13 +0,0 @@
-/**
- * @license
- * Copyright Google LLC All Rights Reserved.
- *
- * Use of this source code is governed by an MIT-style license that can be
- * found in the LICENSE file at https://angular.io/license
- */
-
-/**
- * A constant indicating a type of comparison that NgSwitch uses to match cases. Extracted to a
- * separate file to facilitate G3 patches.
- */
-export const NG_SWITCH_USE_STRICT_EQUALS = true;