Fix EsqlCapabilities to refer to correctly refer to snapshot builds

Author: carlosdelest

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -360,12 +360,12 @@ public enum Cap {
         /**
          * QSTR function
          */
-        QSTR_FUNCTION(true),
+        QSTR_FUNCTION(Build.current().isSnapshot()),
 
         /**
          * MATCH function
          */
-        MATCH_FUNCTION(true),
+        MATCH_FUNCTION(Build.current().isSnapshot()),
 
         /**
          * Don't optimize CASE IS NOT NULL function by not requiring the fields to be not null as well.