Revert "FEATURE: when entering a topic scroll to last visited line marker (#18440)" (#18917)

This reverts commit 136174e0ee.

That worked only 50% of the time (at best), as it was conflicting with other topic-view scrolling code. The reverted feature will eventually be restored as I continue to fix scroll-related issues.

app/assets/javascripts/discourse/app/lib/url.js

@@ -117,15 +117,6 @@ const DiscourseURL = EmberObject.extend({
 
       if (!holder) {
         selector = holderId;
-
-        if (
-          document.getElementsByClassName(
-            `topic-post-visited-line post-${postNumber - 1}`
-          )?.length === 1
-        ) {
-          selector = ".small-action.topic-post-visited";
-        }
-
         holder = document.querySelector(selector);
       }