fix: bound DKG contribution blob intake - #7408

Potential conflicts detected!

{ pull_number: 7408, conflictPrs: [ { number: 7401, files: [ 'src/Makefile.bench.include', 'src/bench/dkg_deserialize.cpp', 'src/llmq/dkgsessionhandler.cpp', 'src/llmq/dkgsessionhandler.h', 'src/llmq/net_dkg.cpp', 'test/util/data/non-backported.txt' ], conflicts: [ 'src/llmq/net_dkg.cpp' ] } ] }