docs(docs-infra): don't use URL to check for external links (#58955)

For perf reasons, it is more efficient to not rely on creating an `URL` object. Instead we check for the explicit protocol to detect external links.

This will also force us to use relative links, so archived versions & next versions navigate on the current version of the site.

fixes #58954

PR Close #58955

adev/src/app/core/layout/secondary-navigation/secondary-navigation.component.ts

@@ -62,7 +62,6 @@ export class SecondaryNavigation implements OnInit {
   private readonly navigationState = inject(NavigationState);
   private readonly platformId = inject(PLATFORM_ID);
   private readonly router = inject(Router);
-  private readonly window = inject(WINDOW);
 
   readonly isSecondaryNavVisible = this.navigationState.isMobileNavVisible;
   readonly primaryActiveRouteItem = this.navigationState.primaryActiveRouteItem;
@@ -83,10 +82,10 @@ export class SecondaryNavigation implements OnInit {
 
   private readonly routeMap: Record<string, NavigationItem[]> = {
     [PagePrefix.REFERENCE]: getNavigationItemsTree(SUB_NAVIGATION_DATA.reference, (tree) =>
-      markExternalLinks(tree, this.window.origin),
+      markExternalLinks(tree),
     ),
     [PagePrefix.DOCS]: getNavigationItemsTree(SUB_NAVIGATION_DATA.docs, (tree) =>
-      markExternalLinks(tree, this.window.origin),
+      markExternalLinks(tree),
     ),
   };