ATR-30800: Rename GN2X working points

Rename GN2X working points based on the study by @rjoshi here.

The old working points were defined by averaging the efficiencies of a serials of RS graviton HH4b samples with different masses. This definition complicates the validation workflow. We now switch to a new definition using the efficiencies of a single sample, the flat mass VHbb sample.

The mapping is as below:

• Old WP -> new WP
• 60% -> 79%
• 70% -> 86%
• 80% -> 91%
• 90% -> 96%

There is no change in the cut values, so no change in trigger counts. Only the trigger names are changed.