HBASE-29037 Backport missing UI patches to branch-2 (apache#6551)

* HBASE-24624 Optimize table.jsp code (apache#1963)

Signed-off-by: Guangxu Cheng <gxcheng@apache.org>
(cherry picked from commit 9ad16aa)

* HBASE-25402 Sorting order by start key or end key is not considering empty start key/end key (apache#2955)

Signed-off-by: Duo Zhang <zhangduo@apache.org>
Signed-off-by: Pankaj Kumar<pankajkumar@apache.org>
(cherry picked from commit 157200e)

* HBASE-28778 NPE may occur when opening master-status or table.jsp or procedure.jsp while Master is initializing (apache#6152)

Signed-off-by: Duo Zhang <zhangduo@apache.org>
(cherry picked from commit 3caaf2d)

* HBASE-20452 Master UI: Table merge button should validate required fields before submit

Signed-off-by: tedyu <yuzhihong@gmail.com>
(cherry picked from commit 6ce1136)

---------
Co-authored-by: xincunSong <365724453@qq.com>
Co-authored-by: Akshay Sudheer <74921542+AkshayTSudheer@users.noreply.github.com>
Co-authored-by: Peng Lu <lupeng_nwpu@qq.com>
Co-authored-by: Nihal Jain <nihaljain.cs@gmail.com>

Signed-off-by: Duo Zhang <zhangduo@apache.org>
Signed-off-by: Nihal Jain <nihaljain.cs@gmail.com>

Author: PDavid

hbase-server/src/main/jamon/org/apache/hadoop/hbase/tmpl/regionserver/RSStatusTmpl.jamon

@@ -299,7 +299,12 @@ $(document).ready(function()
             type: "numeric"
         });
 
-        $("#baseStatsTable").tablesorter();
+        $("#baseStatsTable").tablesorter({
+            headers: {
+                1: {empty: 'emptyMin'},
+                2: {empty: 'emptyMax'}
+            }
+        });
         $("#requestStatsTable").tablesorter({
             headers: {
                 1: {sorter: 'separator'},