When enabling the columnMenu feature in the Grid component, it is also applied to special columns such as the group indicator column or the expand/collapse column. These columns are not user-defined and should not include the column menu.

This leads to a confusing UX where users can click the column menu icon on non-data columns, which serve internal purposes only.

Example: https://stackblitz.com/edit/uj5myrrw?file=src%2Fmain.vue

Expected behavior: Only user-defined data columns should render the column menu icon. Internal columns (like group indicators or row expanders) should not display it.