Prefer Clear over Delete for `AliESDTRDTracklet`s
Prefer Clear over Delete for `AliESDTRDTracklet`s

This is where we spend 80% of the cost when iterating on an ESD collection.
coppedis/AliRoot,alisw/AliRoot,coppedis/AliRoot,coppedis/AliRoot,miranov25/AliRoot,alisw/AliRoot,coppedis/AliRoot,miranov25/AliRoot,miranov25/AliRoot,miranov25/AliRoot,miranov25/AliRoot,coppedis/AliRoot,coppedis/AliRoot,miranov25/AliRoot,alisw/AliRoot,coppedis/AliRoot,miranov25/AliRoot,miranov25/AliRoot,alisw/AliRoot,alisw/AliRoot,alisw/AliRoot,alisw/AliRoot,coppedis/AliRoot,alisw/AliRoot