fix(@angular/cli): prevent Yarn registry environment variable override

When running scripts via Yarn Classic (such as yarn ng update), Yarn automatically injects
npm_config_registry=https://registry.yarnpkg.com into the child process environment.

When the PackageManager abstraction spawns child CLI subprocesses (such as yarn info), those child
processes inherit the injected registry environment variable. Because environment variables take
highest precedence, this previously caused spawned subprocesses to ignore local .yarnrc files and
query the public CDN mirror.

Strip npm_config_registry and NPM_CONFIG_REGISTRY from the child process environment when running
under Yarn so that spawned subprocesses correctly respect local repository registry settings.

Author: clydin

packages/angular/cli/src/package-managers/host.ts

@@ -129,18 +129,33 @@ export const NodeJS_HOST: Host = {
     const isWin32 = platform() === 'win32';
 
     return new Promise((resolve, reject) => {
+      const env: Record<string, string | undefined> = {
+        ...process.env,
+        ...options.env,
+        //  NPM updater notifier will prevents the child process from closing until it timeout after 3 minutes.
+        NO_UPDATE_NOTIFIER: '1',
+        NPM_CONFIG_UPDATE_NOTIFIER: 'false',
+      };
+
+      // When running via Yarn Classic (`yarn run <script>`), Yarn automatically injects
+      // `npm_config_registry=https://registry.yarnpkg.com` into the environment.
+      // Strip this fallback so that spawned child processes correctly respect local `.npmrc`/`.yarnrc` files.
+      if (
+        (env['npm_config_registry'] === 'https://registry.yarnpkg.com' ||
+          env['NPM_CONFIG_REGISTRY'] === 'https://registry.yarnpkg.com') &&
+        (env['npm_config_user_agent']?.includes('yarn') ||
+          env['NPM_CONFIG_USER_AGENT']?.includes('yarn'))
+      ) {
+        delete env['npm_config_registry'];
+        delete env['NPM_CONFIG_REGISTRY'];
+      }
+
       const spawnOptions = {
         shell: isWin32,
         stdio: options.stdio ?? 'pipe',
         signal,
         cwd: options.cwd,
-        env: {
-          ...process.env,
-          ...options.env,
-          //  NPM updater notifier will prevents the child process from closing until it timeout after 3 minutes.
-          NO_UPDATE_NOTIFIER: '1',
-          NPM_CONFIG_UPDATE_NOTIFIER: 'false',
-        },
+        env,
       } satisfies SpawnOptions;
       const childProcess = isWin32
         ? spawn(`${command} ${args.join(' ')}`, spawnOptions)