Remove unused const "DuplicateLeaf"
Remove unused const "DuplicateLeaf"

AlCutter/trillian,Martin2112/trillian,codingllama/trillian,RJPercival/trillian,daviddrysdale/trillian,daviddrysdale/trillian,daviddrysdale/trillian,Martin2112/trillian,RJPercival/trillian,Martin2112/trillian,google/trillian,codingllama/trillian,AlCutter/trillian,gdbelvin/trillian,gdbelvin/trillian,google/trillian,gdbelvin/trillian