test: skip internet for test-npm-install

Disabling any internet-required features (namely audit and
update-notifer) in order for the test to work without an internet
connection.

- Fixes: #36895

test/parallel/test-npm-install.js

@@ -42,6 +42,8 @@ const env = { ...process.env,
               PATH: path.dirname(process.execPath),
               NPM_CONFIG_PREFIX: path.join(npmSandbox, 'npm-prefix'),
               NPM_CONFIG_TMP: path.join(npmSandbox, 'npm-tmp'),
+              NPM_CONFIG_AUDIT: false,
+              NPM_CONFIG_UPDATE_NOTIFIER: false,
               HOME: homeDir,
 };