Cleanup logging statements (#1500)

A few logging statements had errors in the log statement.  Either the
parameter wasn't used or it was expecting a formatted logger for errors.

Signed-off-by: Danno Ferrin <danno.ferrin@gmail.com>

consensus/ibft/src/main/java/org/hyperledger/besu/consensus/ibft/EventMultiplexer.java

@@ -57,7 +57,7 @@ public class EventMultiplexer {
           throw new RuntimeException("Illegal event in queue.");
       }
     } catch (final Exception e) {
-      LOG.error("State machine threw exception while processing event {" + ibftEvent + "}", e);
+      LOG.error("State machine threw exception while processing event \\{" + ibftEvent + "\\}", e);
     }
   }
 }

ethereum/permissioning/src/main/java/org/hyperledger/besu/ethereum/permissioning/TomlConfigFileParser.java

@@ -68,7 +68,7 @@ public class TomlConfigFileParser {
       }
       if (!tomlConfigFile.canWrite()) {
         LOG.warn(
-            "Write access denied for file at: %s. Configuration modification operations will not be permitted.",
+            "Write access denied for file at: {}. Configuration modification operations will not be permitted.",
             filename);
       }
       return tomlConfigFile;

nat/src/main/java/org/hyperledger/besu/nat/NatService.java

@@ -192,7 +192,8 @@ public class NatService {
         final NatManager natManager = getNatManager().orElseThrow();
         return Optional.of(natManager.getPortMapping(serviceType, networkProtocol));
       } catch (Exception e) {
-        LOG.warn("Caught exception while trying to query port mapping (ignoring): {}", e);
+        LOG.warn(
+            "Caught exception while trying to query port mapping (ignoring): {}", e.toString());
       }
     }
     return Optional.empty();