Apply suggestions from code review

Co-authored-by: Burak Yigit Kaya <ben@byk.im>

Author: BYK

src/types/dashboard.ts

@@ -270,7 +270,6 @@ export type SpanAggregateFunction = (typeof SPAN_AGGREGATE_FUNCTIONS)[number];
 export const DISCOVER_AGGREGATE_FUNCTIONS = [
   ...SPAN_AGGREGATE_FUNCTIONS,
   "failure_count",
-  "failure_rate",
   "apdex",
   "count_miserable",
   "user_misery",