Revert "In our project, we need to fix one column to the far right of the grid; new columns should always be inserted left of that one. To overcome this, I'm now pushing new columns based on the index in columnDefs. This results in columnDef representing the actual column ordering within the grid."

This reverts commit a5af65bb7fc893b612fc884e4c4eddd7572694fe.
Revert "Revert "In our project, we need to fix one column to the far right of the grid; new columns should always be inserted left of that one. To overcome this, I'm now pushing new columns based on the index in columnDefs. This results in columnDef representing the actual column ordering within the grid.""

This reverts commit 4369d5af6fd550a741c43bb91d70446229095587.