refactor: move Wombat registry to reusable constant

Pure refactor that just pulls the Wombat registry into a separate string constant to be re-used across scripts.

lib/registries.ts

@@ -0,0 +1,10 @@
+/**
+ * @license
+ * Copyright Google Inc. 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
+ */
+
+/** URL to Wombat NPM registry proxy. */
+export const wombat = 'https://wombat-dressing-room.appspot.com';

scripts/publish.ts

@@ -10,9 +10,9 @@ import { logging, tags } from '@angular-devkit/core';
 import { spawnSync } from 'child_process';
 import * as semver from 'semver';
 import { packages } from '../lib/packages';
+import { wombat } from '../lib/registries';
 import build from './build';
 
-
 export interface PublishArgs {
   tag?: string;
   branchCheck?: boolean;
@@ -118,7 +118,7 @@ export default async function (args: PublishArgs, logger: logging.Logger) {
         }
 
         // If no registry is provided, the wombat proxy should be used.
-        publishArgs.push('--registry', args.registry || 'https://wombat-dressing-room.appspot.com');
+        publishArgs.push('--registry', args.registry ?? wombat);
 
         return _exec('npm', publishArgs, {
           cwd: pkg.dist,