I3highestparticleextractor mctree particle changed

[Aske-Rosted]

Describe the bug
Found a pesky bug where the values of some of the particles in the mctree are unintentionally overwritten leading to following calls of the mctree producing unexpected results. This produced no errors when running just a single I3highestparticleextractor. but when running two I ran into length mismatches between MuonGun_tracks and MMCTrackList defined at

graphnet/src/graphnet/data/extractors/icecube/i3highesteparticleextractor.py

Line 273 in 5fe7f9f

MuonGun_tracks, MMCTrackList = self.get_tracks(frame)

To Reproduce
run an extractor with two instances of the I3highestparticleextractor.

Additional context
I have implemented a fix and will committing a PR