[MINOR] Fixed pruning help (default: false) (#1073)

Fixed pruning help (default: false)

Signed-off-by: Sally MacFarlane <sally.macfarlane@consensys.net>

besu/src/main/java/org/hyperledger/besu/cli/BesuCommand.java

@@ -764,7 +764,7 @@ public class BesuCommand implements DefaultCommandValues, Runnable {
   @Option(
       names = {"--pruning-enabled"},
       description =
-          "Enable disk-space saving optimization that removes old state that is unlikely to be required (default: true if fast sync is enabled, false otherwise)")
+          "Enable disk-space saving optimization that removes old state that is unlikely to be required (default: ${DEFAULT-VALUE})")
   private final Boolean pruningEnabled = false;
 
   @Option(