hydra-plutus: Remove unused functions #5949

Job	Run time
Build haddock using nix	1m 51s
Benchmarks (hydra-node, tx-cost, --output-directory $(pwd)/../benchmarks)	3m 6s
Build & test (plutus-cbor)	1m 59s
nix flake check	5m 15s
Benchmarks (hydra-node, micro, -o $(pwd)/../benchmarks/ledger-bench.html)	2m 24s
Build & test (plutus-merkle-tree)	1m 51s
Benchmarks (hydra-cluster, bench-e2e, datasets datasets/1-node.json datasets/3-nodes.json --outpu...	4m 44s
Build & test (hydra-plutus)	2m 23s
Build & test (hydra-tui)	4m 15s
Benchmarks (plutus-merkle-tree, on-chain-cost, $(pwd)/../benchmarks)	2m 10s
Build & test (hydra-node)	7m 30s
Build specification using nix	2m 23s
Build & test (hydra-tx)	2m 43s
Build & test (hydra-cluster)	9m 14s
Publish benchmark results	5s
Documentation	3m 19s
Publish test results	15s
	55m 27s

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