downgrade logs in miner to debug (#5179)

closes: #5167

downgrades info log that atx are omitted from activeset. this is a part of heuristic to decide if node should use atxs based on grades or fallback to activeset recorded in first block (for example it may happen if node wasn't fully synced before epoch start).

and downgrades log that smesher doesn't have atx.

miner/proposal_builder.go

@@ -493,7 +493,7 @@ func (pb *ProposalBuilder) build(ctx context.Context, lid types.LayerID) error {
 		eg.Go(func() error {
 			if err := pb.initSignerData(ctx, ss, lid); err != nil {
 				if errors.Is(err, errAtxNotAvailable) {
-					ss.log.With().Info("smesher doesn't have atx that targets this epoch",
+					ss.log.With().Debug("smesher doesn't have atx that targets this epoch",
 						log.Context(ctx), ss.session.epoch.Field(),
 					)
 				} else {
@@ -727,7 +727,7 @@ func generateActiveSet(
 			return err
 		}
 		if grade != good {
-			logger.With().Info("atx omitted from active set",
+			logger.With().Debug("atx omitted from active set",
 				header.ID,
 				log.Int("grade", int(grade)),
 				log.Stringer("smesher", header.NodeID),