Fix test error message

Author: carlosdelest

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/esql/180_match_operator.yml

@@ -199,4 +199,4 @@ setup:
 
   - match: { status: 400 }
   - match: { error.type: verification_exception }
-  - match: { error.reason: "/.*[:] operator is only supported in WHERE.*/" }
+  - match: { error.reason: "/.*operator.is.only.supported.in.WHERE.*/" }