fix(events-trace-meta): Remove indexed spans usage (#95374)

The only orgs still using this endpoint should not have any data in
indexed spans. So we can remove this query.

Author: Zylphrex

src/sentry/api/endpoints/organization_events_trace.py

@@ -1767,32 +1767,12 @@ def get(self, request: Request, organization: Organization, trace_id: str) -> Ht
             query=f"trace:{trace_id}",
             limit=1,
         )
-        transaction_children_query = SpansIndexedQueryBuilder(
-            dataset=Dataset.SpansIndexed,
-            selected_columns=[
-                "transaction.id",
-                "count()",
-            ],
-            orderby=["transaction.id"],
-            params={},
-            snuba_params=snuba_params,
-            query=f"trace:{trace_id}",
-            limit=10_000,
-        )
 
         with handle_query_errors():
-            results = bulk_snuba_queries(
-                [
-                    meta_query.get_snql_query(),
-                    transaction_children_query.get_snql_query(),
-                ],
+            meta_result = meta_query.run_query(
                 referrer=Referrer.API_TRACE_VIEW_GET_META.value,
                 query_source=query_source,
             )
-            meta_result, children_result = (
-                results[0],
-                results[1],
-            )
             if len(meta_result["data"]) == 0:
                 return Response(status=404)
             # Merge the result back into the first query
@@ -1804,22 +1784,20 @@ def get(self, request: Request, organization: Organization, trace_id: str) -> Ht
         return Response(
             self.serialize(
                 meta_result["data"][0],
-                children_result["data"],
             )
         )
 
     def serialize(
         self,
         results: Mapping[str, int],
-        child_result: Any,
-    ) -> Mapping[str, int | dict[str, int]]:
+    ) -> Mapping[str, int | dict[str, int] | list[Any]]:
         return {
             # Values can be null if there's no result
             "projects": results.get("projects") or 0,
             "transactions": results.get("transactions") or 0,
             "errors": results.get("errors") or 0,
             "performance_issues": results.get("performance_issues") or 0,
             "span_count": 0,
-            "transaction_child_count_map": child_result,
+            "transaction_child_count_map": [],
             "span_count_map": {},
         }

tests/snuba/api/endpoints/test_organization_events_trace.py

@@ -1763,4 +1763,4 @@ def test_with_default(self):
         assert data["performance_issues"] == 2
         assert data["span_count"] == 0
         assert data["span_count_map"] == {}
-        assert len(data["transaction_child_count_map"]) == 8
+        assert len(data["transaction_child_count_map"]) == 0