Bug#25876807: FOR DIFFERENT VERSION (5.7 AND 5.8) GROUP, LEADER SHOULD BE ONLY FROM 5.7

Updating missing @param lowest_version_end definition for
sort_members_for_election() and removing @param lowest_version_end
for sort_and_get_lowest_version_member_position() in gcs_event_handlers.h
for Group Replication plugin.

Author: Hemant Dangi

rapid/plugin/group_replication/include/gcs_event_handlers.h

@@ -135,9 +135,9 @@ class Plugin_gcs_events_handler: public Gcs_communication_event_listener,
   /**
     Sort lower version members based on uuid
 
-    @param all_members_info   the vector with members info
-
-    @return first iterator position where members version increase.
+    @param all_members_info    the vector with members info
+    @param lowest_version_end  first iterator position where members version
+                               increases.
    */
   void sort_members_for_election(
        std::vector<Group_member_info*>* all_members_info,
@@ -148,8 +148,8 @@ class Plugin_gcs_events_handler: public Gcs_communication_event_listener,
     where member version differs.
 
     @param all_members_info    the vector with members info
-    @param lowest_version_end  first iterator position where members version
-                               increases.
+
+    @return  the first iterator position where members version increase.
 
     @note from the start of the list to the returned iterator, all members have
           the lowest version in the group.