HBASE-27504 Remove duplicated config 'hbase.normalizer.merge.min_region_age.days' in hbase-default.xml (#4894)

Signed-off-by: Duo Zhang <[email protected]>

Author: mokai87

hbase-common/src/main/resources/hbase-default.xml

@@ -660,11 +660,6 @@ possible configurations would overwhelm and obscure the important.
     <value>3</value>
     <description>The minimum age for a region to be considered for a merge, in days.</description>
   </property>
-  <property>
-    <name>hbase.normalizer.merge.min_region_age.days</name>
-    <value>3</value>
-    <description>The minimum age for a region to be considered for a merge, in days.</description>
-  </property>
   <property>
     <name>hbase.normalizer.merge.min_region_size.mb</name>
     <value>1</value>