SelectColumnLayer to only allow cross-column parallelization if its S…

…electColumn is stateless

engine/table/src/main/java/io/deephaven/engine/table/impl/select/analyzers/SelectColumnLayer.java

@@ -568,6 +568,6 @@ public LogOutput append(LogOutput logOutput) {
 
     @Override
     public boolean allowCrossColumnParallelization() {
-        return inner.allowCrossColumnParallelization();
+        return selectColumn.isStateless() && inner.allowCrossColumnParallelization();
     }
 }