PERF: Remove custom Sidebar::SectionLinkTo implementation

This custom implementation was extending from `Ember.LinkComponent`, which is a legacy 'classic component' implementation of `<LinkTo`. Our current version of Ember includes a native glimmer implementation of LinkTo which should be much faster.

The patch we introduced was to set the 5th argument to `routing.isActiveForRoute` to `false`. In our current version of Ember, `isActiveForRoute` only takes 4 arguments, so this override is essentially a no-op. The change was made in https://github.com/emberjs/ember.js/commit/56af48bb41 (first released in Ember 3.24).

app/assets/javascripts/discourse/app/components/sidebar/section-link-to.js

@@ -1,51 +0,0 @@
-import Ember from "ember";
-
-export default class SidebarSectionLinkTo extends Ember.LinkComponent {
-  // Overriding the private function here because the behavior of the component when used with the `current-when`
-  // attribute does not seem to follow what was mentioned in the docs: "A link will be active if current-when is true or
-  // the current route is the route this link would transition to". When the `current-when` attribute is used, the
-  // `route` and `query` attributes are ignored which is not what we want. In addition, we're stuck on Ember 3.15 at
-  // the moment and are awaiting the upgrade to the latest supported Ember version before I can determine if this is a
-  // bug and report it as such.
-  _isActive(routerState) {
-    if (this.loading) {
-      return false;
-    }
-
-    let currentWhen = this["current-when"];
-
-    if (typeof currentWhen === "boolean") {
-      return currentWhen;
-    }
-
-    let isCurrentWhenSpecified = Boolean(currentWhen);
-
-    if (isCurrentWhenSpecified) {
-      currentWhen = currentWhen.split(" ");
-    } else {
-      currentWhen = [this._route];
-    }
-
-    let { _models: models, _query: query, _routing: routing } = this;
-
-    for (let i = 0; i < currentWhen.length; i++) {
-      if (
-        routing.isActiveForRoute(
-          models,
-          query,
-          currentWhen[i],
-          routerState,
-          // **custom code override start**
-          // we always want query params to be considered
-          false
-          // isCurrentWhenSpecified
-          // **custom code override end**
-        )
-      ) {
-        return true;
-      }
-    }
-
-    return false;
-  }
-}

app/assets/javascripts/discourse/app/components/sidebar/section-link.hbs

@@ -25,13 +25,13 @@
         </span>
       </a>
     {{else}}
-      <Sidebar::SectionLinkTo
-        @class={{this.classNames}}
+      <LinkTo
+        class={{this.classNames}}
         @route={{@route}}
         @query={{@query}}
         @models={{this.models}}
         @current-when={{@currentWhen}}
-        @title={{@title}}
+        title={{@title}}
       >
 
         <Sidebar::SectionLinkPrefix
@@ -86,7 +86,7 @@
             </button>
           </span>
         {{/if}}
-      </Sidebar::SectionLinkTo>
+      </LinkTo>
     {{/if}}
   </li>
 {{/if}}