[ATR-22366] Python bug fix to xAOD trigger menu check

In 22.0.18 in test_q221.sh we see

Py:TriggerConfigGetter.py    INFO ESD/AOD writing enabled, will set up xAOD trigger configuration metadata writing

whereas sometime after this, we no longer see this line.

This is due to an issue in the hasxAODMeta flag.

Fixing 🐛 introduced by !37159 (merged)