Fix error in xpack usage

Author: afoucret

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

@@ -131,7 +131,7 @@ setup:
   - gt: {esql.functions.to_long: $functions_to_long}
   - match: {esql.functions.coalesce: $functions_coalesce}
   - gt: {esql.functions.categorize: $functions_categorize}
-  - match: {esql.functions.text_embedding: functions_text_embedding}
+  - match: {esql.functions.text_embedding: $functions_text_embedding}
   # Testing for the entire function set isn't feasible, so we just check that we return the correct count as an approximation.
   - length: {esql.functions: 180} # check the "sister" test below for a likely update to the same esql.functions length check
 ---