test(@angular-devkit/build-angular): update E2E test to use node-sass version 5

The current version of sass-loader doesn't support node-sass@6

Author: alan-agius4

tests/legacy-cli/e2e/tests/build/styles/node-sass.ts

@@ -33,7 +33,7 @@ export default async function () {
   await silentExec('rm', '-rf', 'node_modules/sass');
   await expectToFail(() => ng('build', '--extract-css', '--source-map'));
 
-  await installPackage('node-sass');
+  await installPackage('node-sass@5');
   await silentExec('rm', '-rf', 'node_modules/sass');
   await ng('build', '--extract-css', '--source-map');