update analytics in generate api docs site to use new UA4 (#136497)

Change the analytics instance that the generated api.flutter.dev and master-api.flutter.dev use.

dev/docs/analytics-footer.html

@@ -0,0 +1,4 @@
+<!-- Google Tag Manager (noscript) -->
+<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-ND4LWWZ"
+height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
+<!-- End Google Tag Manager (noscript) -->

dev/docs/analytics-header.html

@@ -0,0 +1,7 @@
+<!-- Google Tag Manager -->
+<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
+new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
+j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
+'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f)
+})(window,document,'script','dataLayer','GTM-ND4LWWZ');</script>
+<!-- End Google Tag Manager -->

dev/docs/analytics.html

@@ -1,9 +0,0 @@
-<script>
-  (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
-  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
-  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
-  })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
-
-  ga('create', 'UA-67589403-1', 'auto');
-  ga('send', 'pageview');
-</script>