Dataframe is heavily fragmented, in config/design_matrix.py

[berland]

This warning should probably be solved:

/prog/res/komodo/bleeding-20250225-0207-py311-rhel8/root/lib64/python3.11/site-packages/ert/config/design_matrix.py:201: 
PerformanceWarning: DataFrame is highly fragmented.  This is usually the result of calling `frame.insert` many times,
 which has poor performance.  Consider joining all columns at once using pd.concat(axis=1) 
instead. To get a de-fragmented frame, use `newframe = frame.copy()`