ci(docs-infra): manually trigger the preview server webhook (#27458)

With this change, we no longer depend on CircleCI to trigger the webhook
(which it sometimes does with considerable delay or not at all).

This has the added benefit that other jobs will not unnecessarily
trigger webhooks and spam the preview server logs. It is only the
`aio_preview` job's webhook that we care about.

Related to #27352.

PR Close #27458

aio/scripts/create-preview.js

@@ -0,0 +1,37 @@
+#!/usr/bin/env node
+
+/**
+ * Usage:
+ *   node create-preview <build-number>
+ *
+ * Triggers the preview server to initiate the preview creation process for the specified CircleCI
+ * build number. It must be called _after_ the build artifacts have been created and stored on
+ * CircleCI.
+ */
+
+// Imports
+const {triggerWebhook} = require('../../.circleci/trigger-webhook');
+
+// Constants
+const JOB_NAME = 'aio_preview';
+const WEBHOOK_URL = 'https://ngbuilds.io/circle-build';
+
+// Input
+const buildNumber = process.argv[2];
+
+// Run
+triggerWebhook(buildNumber, JOB_NAME, WEBHOOK_URL).
+  then(({statusCode, responseText}) => isSuccess(statusCode) ?
+    console.log(`Status: ${statusCode}\n${responseText}`) :
+    Promise.reject(new Error(`Request failed (status: ${statusCode}): ${responseText}`))).
+  catch(err => {
+    console.error(err);
+    process.exit(1);
+  });
+
+// Helpers
+function isSuccess(statusCode) {
+  // Getting a 409 response from the preview server means that the preview has already been created
+  // for the corresponding PR/SHA, so our objective has been accomplished.
+  return (200 <= statusCode && statusCode < 400) || (statusCode === 409);
+}