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

ci/localnet-sanity.sh

@@ -294,7 +294,7 @@ flag_error() {
 }
 
 if ! $skipSetup; then
-  multinode-demo/setup.sh
+  multinode-demo/setup.sh --hashes-per-tick auto
 else
   verifyLedger
 fi