fix(lib): update scripts/aem.js to aem.js@2.5.2 (#391)

Test URL: https://update-lib-aem-patch-2-5-2--aem-boilerplate--adobe.hlx.live/
Release Notes: https://github.com/adobe/aem-lib/releases/tag/v2.5.2

Co-authored-by: semantic-release-bot <semantic-release-bot@martynus.net>

scripts/aem.js

@@ -18,7 +18,10 @@ function sampleRUM(checkpoint, data) {
     window.hlx = window.hlx || {};
     sampleRUM.enhance = () => {};
     if (!window.hlx.rum) {
-      const weight = new URLSearchParams(window.location.search).get('rum') === 'on' ? 1 : 100;
+      const weight = (window.SAMPLE_PAGEVIEWS_AT_RATE === 'high' && 10)
+        || (window.SAMPLE_PAGEVIEWS_AT_RATE === 'low' && 1000)
+        || (new URLSearchParams(window.location.search).get('rum') === 'on' && 1)
+        || 100;
       const id = Math.random().toString(36).slice(-4);
       const isSelected = Math.random() * weight < 1;
       // eslint-disable-next-line object-curly-newline, max-len