Reduced logging level on Subscriber error callback. (#4485)

Signed-off-by: mark-terry <mark.terry@consensys.net>

Signed-off-by: mark-terry <mark.terry@consensys.net>
Co-authored-by: Sally MacFarlane <macfarla.github@gmail.com>

util/src/main/java/org/hyperledger/besu/util/Subscribers.java

@@ -112,7 +112,7 @@ public class Subscribers<T> {
                 action.accept(subscriber);
               } catch (final Exception e) {
                 if (suppressCallbackExceptions) {
-                  LOG.error("Error in callback: {}", e.getMessage());
+                  LOG.info("Error in callback: {}", e.getMessage());
                   LOG.debug("Error in callback: ", e);
                 } else {
                   throw e;