[TEST] Fix check for avg_over_time counter (#135637)

Fixes #135579 Fixes #135580 Fixes #135581 Fixes #135582 Fixes #135584

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/esql/60_usage.yml

@@ -201,7 +201,7 @@ setup:
   - gt: { esql.queries._all.total: $all_total_counter }
   - match: { esql.queries._all.failed: $all_failed_counter }
   - gt: { esql.functions.min: $functions_min }
-  - gt: { esql.functions.min: $functions_avg_over_time }
+  - gt: { esql.functions.avg_over_time: $functions_avg_over_time }
 
   # There's one of these per function but that's a ton of things to check. So we just spot check that a few exist.
   - exists: esql.functions.delay