Fix bug in run_athena CI job when running on multiple LHE input files

Description of bug

In run_athena.sh the generate command was printing files with a new line character at the end so if there were more than 1 input files it would only use one input file for the athena run and logParser would crash as in !1195 (merged)

Changes introduced

Print comma separated list of files when calling Gen_tf.py command

Tests

See !1195 (merged)

Issues resolved

Closes #