Revert "🤖 Fix TypeError in mergeItems Function (#67009)"

This reverts commit 9d1ab7d73fd8716b677d5de6ee76823e1dbf544b.

Co-authored-by: JoshFerge <1976777+JoshFerge@users.noreply.github.com>

static/app/stores/groupStore.tsx

@@ -119,9 +119,7 @@ const storeConfig: GroupStoreDefinition = {
   },
 
   mergeItems(items: Item[]) {
-    const itemsById = items
-      .filter(item => item && typeof item.id !== 'undefined')
-      .reduce((acc, item) => ({...acc, [item.id]: item}), {});
+    const itemsById = items.reduce((acc, item) => ({...acc, [item.id]: item}), {});
 
     // Merge these items into the store and return a mapping of any that aren't already in the store
     this.items.forEach((item, itemIndex) => {