Fix error in locating control files

Description of bug

Due to !3578 (merged) when e.g. include("PowhegControl/PowhegControl_ggF_HH_Common.py") was included the script would crash because it would not be able to find it in the DSID directory (since it's located in athena)

Changes introduced

Skip control file checks if control find cannot be found

Tests

Tested with failing pipeline

Issues resolved

Closes #