ES|QL: relax tests on usage stats (#115214)

Author: luigidellaquila

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

@@ -83,4 +83,3 @@ setup:
   - match: {esql.functions.cos: $functions_cos}
   - gt: {esql.functions.to_long: $functions_to_long}
   - match: {esql.functions.coalesce: $functions_coalesce}
-  - length: {esql.functions: 117}