Disable CTAS by default (#9057)

Author: nikvas0

ydb/core/protos/table_service_config.proto

@@ -285,7 +285,7 @@ message TTableServiceConfig {
     optional bool EnableOlapSink = 55 [default = false];
 
     optional bool EnablePerStatementQueryExecution = 56 [default = false];
-    optional bool EnableCreateTableAs = 57 [default = true];
+    optional bool EnableCreateTableAs = 57 [default = false];
 
     optional uint64 IdxLookupJoinPointsLimit = 58 [default = 3];
     reserved 59; //optional bool OldLookupJoinBehaviour = 59 [default = false];