DON-518: Fix Scrolling in explore page doesn't load more cards

Initially tried copying code from the old explore page at
https://github.com/thebiggive/donate-frontend/blob/36cc52e9a883fe1e33b013e1515503ee574fb3b7/src/app/explore/explore.component.ts#L162

but that actually just does the same thing as the `doCampaignSearch`
function that we already have, so we just need to call that
unconditionally for both the campaign and explore pages.

Also switched away from the deprecated usage of Observable.subscribe
with two params

src/app/explore/explore.component.ts

@@ -357,6 +357,7 @@ export class ExploreComponent implements AfterViewChecked, OnDestroy, OnInit {
   }
 
   private loadMoreForCurrentSearch() {
+    console.log("in loadmoreForCurrentSearch");
     this.offset += CampaignService.perPage;
     this.loading = true;
     const query = this.campaignService.buildQuery(
@@ -367,9 +368,7 @@ export class ExploreComponent implements AfterViewChecked, OnDestroy, OnInit {
       this.fundSlug,
     );
 
-    if (this.metaCampaign) {
-      this.doCampaignSearch(query as SearchQuery, false);
-    }
+    this.doCampaignSearch(query as SearchQuery, false);
   }
 
   /**