Poh subsystem cleanup, genesis plumbing, enable real PoH on edge testnet (#4292)

* Remove unused PohServiceConfig::Step

* Clarify variable name

* Poh::hash() now takes an iteration counter

* man -> max

* Inline functions with single call site

* Move PohServiceConfig into GenesisBlock

* Add plumbing to enable real PoH on testnets

* Batch hashes to improve PoH hash rate

* Ensure a constant hashes_per_tick

* Remove PohEntry mixin field

* Poh/PohEntry no longer maintains tick_height

* Ensure a constant hashes_per_tick

* ci/localnet-sanity.sh: Use real PoH

* Rework Poh/PohService to keep PohRecorder unlocked as much as possible while hashing

core/tests/tvu.rs

@@ -90,6 +90,7 @@ fn test_replay() {
         ledger_signal_receiver,
         completed_slots_receiver,
         leader_schedule_cache,
+        _,
     ) = fullnode::new_banks_from_blocktree(&blocktree_path, None);
     let working_bank = bank_forks.working_bank();
     assert_eq!(