Normalize the usage of debug logs in NameNode

if (LOG.isDebugEnabled()) {
      LOG.debug("Getting groups for user " + user);
}

LOG.debug("Getting groups for user {}. ", user);

LOG.debug("*DIR* NameNode.renameSnapshot: Snapshot Path {}, " +
        "snapshotOldName {}, snapshotNewName {}", snapshotRoot,
        snapshotOldName, snapshotNewName);

if (LOG.isDebugEnabled()) {
  LOG.debug("*DIR* NameNode.renameSnapshot: Snapshot Path {}, " +
        "snapshotOldName {}, snapshotNewName {}", snapshotRoot,
        snapshotOldName, snapshotNewName); 
}

if (LOG.isDebugEnabled()) {
      LOG.debug("getAdditionalDatanode: src=" + src
          + ", fileId=" + fileId
          + ", blk=" + blk
          + ", existings=" + Arrays.asList(existings)
          + ", excludes=" + Arrays.asList(excludes)
          + ", numAdditionalNodes=" + numAdditionalNodes
          + ", clientName=" + clientName);
    }

 if (LOG.isDebugEnabled()) {
   LOG.debug("getAdditionalDatanode: src={}, fileId={}, "
           + "blk={}, existings={}, excludes={}, numAdditionalNodes={}, "
          + "clientName={}.", src, fileId, blk, Arrays.asList(existings),
          Arrays.asList(excludes), numAdditionalNodes, clientName);
 }