test(@angular/cli): remove unscoped authentication test cases from registry tests

Modern package managers do not support unscoped authentication, and Yarn Classic's
metadata command (yarn info) does not propagate unscoped credentials correctly,
leading to 403 Forbidden failures on secure registries during ng update and ng add.

This commit removes the unscoped authentication test cases from both add and
update secure registry E2E tests, and cleans up the
createNpmConfigForAuthentication helper to default to scoped authentication.

Author: clydin

tests/e2e/tests/update/update-secure-registry.ts

@@ -6,9 +6,6 @@ import { getActivePackageManager } from '../../utils/packages';
 import assert from 'node:assert';
 
 export default async function () {
-  const packageManager = getActivePackageManager();
-  const supportsUnscopedAuth = packageManager === 'yarn';
-
   // The environment variable has priority over the .npmrc
   delete process.env['NPM_CONFIG_REGISTRY'];
   const worksMessage = 'We analyzed your package.json';
@@ -20,14 +17,6 @@ export default async function () {
 
   // Valid authentication token
 
-  if (supportsUnscopedAuth) {
-    await createNpmConfigForAuthentication(false);
-    const { stdout: stdout1 } = await ng('update', ...extraArgs);
-    if (!stdout1.includes(worksMessage)) {
-      throw new Error(`Expected stdout to contain "${worksMessage}"`);
-    }
-  }
-
   await createNpmConfigForAuthentication(true);
   const { stdout: stdout2 } = await ng('update', ...extraArgs);
   if (!stdout2.includes(worksMessage)) {
@@ -36,11 +25,6 @@ export default async function () {
 
   // Invalid authentication token
 
-  if (supportsUnscopedAuth) {
-    await createNpmConfigForAuthentication(false, true);
-    await expectToFail(() => ng('update', ...extraArgs));
-  }
-
   await createNpmConfigForAuthentication(true, true);
   await expectToFail(() => ng('update', ...extraArgs));