A crash on startup happens on --chain=mumbai , because I've confused
chainConfig.Bor (from type chain.Config) and config.Bor (from type
ethconfig.Config) in the setup code.
ethconfig.Config.Bor property contained bogus values, and was used only
to check its type in CreateConsensusEngine(). Its value was never read
(before PR #9117).
This change removes the property to avoid confusion and fix the crash.
Devnet network.BorStateSyncDelay was implemented using
ethconfig.Config.Bor, but it wasn't taking any effect. It should be
fixed separately in a different way.
ebe16d8360