PROCTools: Toggle --nan-equal while running diff-root in RunTier0Tests.py

Alaettin Serhan Meterequested to merge
amete/athena:master-ATLASRECTS-5722 into master

FTAG writes out NaNs in certain cases and the standard dictates NaN!=NaN. This now affects the primary AODs in master so we're making --nan-equal the default in RunTier0Test.py.

Closes ATLASRECTS-5722

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