Fixing sub logging and moving stack trace to debug. (#4334)

* Fixing sub logging and moving stack trace to debug.

Signed-off-by: Matt Nelson <matt.nelson@consensys.net>
Co-authored-by: Matt Nelson <matt.nelson@Matts-MacBook-Pro.local>

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

@@ -112,7 +112,8 @@ public class Subscribers<T> {
                 action.accept(subscriber);
               } catch (final Exception e) {
                 if (suppressCallbackExceptions) {
-                  LOG.error("Error in callback: ", e);
+                  LOG.error("Error in callback: {}", e.getMessage());
+                  LOG.debug("Error in callback: ", e);
                 } else {
                   throw e;
                 }