Define knownPools in terms of listRegisteredPools.

There's no point in fetching the entire set of all pool-related data
when all we really need is the set of valid pool IDs.

lib/shelley/src/Cardano/Wallet/Shelley/Pools.hs

@@ -147,6 +147,7 @@ import qualified Cardano.Wallet.Api.Types as Api
 import qualified Data.List as L
 import qualified Data.Map.Merge.Strict as Map
 import qualified Data.Map.Strict as Map
+import qualified Data.Set as Set
 
 --
 -- Stake Pool Layer
@@ -194,7 +195,7 @@ newStakePoolLayer nl db@DBLayer {..} =
  _knownPools
  :: IO (Set PoolId)
  _knownPools =
- Map.keysSet <$> liftIO (readPoolDbData db minBound)
+ Set.fromList <$> liftIO (atomically listRegisteredPools)
 
  _listPools
  :: EpochNo