EnhancedBiasWeights: Add script to create helper xml

Add script to create xml file needed for the Enhanced Bias event weighting with additional run information.

The average deadtime is read from TRP using pbeast. Luminosity and pileup is read from COOL

Compared to Run 2, some values from lumivalues section were removed and the list of eb chains' seeds - that information is no longer needed

Run 2 file example: /cvmfs/atlas.cern.ch/repo/sw/database/GroupData/TrigCostRootAnalysis/enhanced_bias_run_360026.xml

Run 3 file for run 428855: /afs/cern.ch/work/a/aporeba/public/TrigCostRootAnalysis/enhanced_bias_run_428855.xml

Tagging @tamartin