[gatsby-plugin-vercel-analytics] Remove "babel" compilation (#10546)

The "babel" build for this package essentially does nothing. The output is still using ESM and no transformation is done. Let's just remove the "build" script entirely.

packages/gatsby-plugin-vercel-analytics/gatsby-browser.js

@@ -0,0 +1,17 @@
+import { webVitals } from "./web-vitals";
+
+export const onClientEntry = (_, pluginOptions = {}) => {
+  let options = {
+    debug: false,
+    ...pluginOptions,
+    analyticsId: process.env.GATSBY_VERCEL_ANALYTICS_ID,
+  };
+
+  if (!options.analyticsId) {
+    return null;
+  }
+
+  if (options.debug || process.env.NODE_ENV === "production") {
+    webVitals({ options });
+  }
+};