polkadot: disable block authoring backoff on production networks (#2510)

Currently the polkadot node will backoff from block authoring if
finality starts lagging. This PR disables this mechanism on production
networks (polkadot and kusama) and adds a flags to optionally force
enabling it.

polkadot/parachain/test-parachains/undying/collator/src/main.rs

@@ -84,6 +84,7 @@ fn main() -> Result<()> {
 						),
 						grandpa_pause: None,
 						enable_beefy: false,
+						force_authoring_backoff: false,
 						jaeger_agent: None,
 						telemetry_worker_handle: None,