fix mysql init for ubuntu 16.04

install/ubuntu/16.04/mysql/my-large.cnf

@@ -28,7 +28,6 @@ read_rnd_buffer_size = 4M
 myisam_sort_buffer_size = 64M
 thread_cache_size = 8
 query_cache_size= 16M
-thread_concurrency = 8
 
 #innodb_use_native_aio = 0
 innodb_file_per_table

install/vst-install-ubuntu.sh

@@ -932,7 +932,9 @@ if [ "$mysql" = 'yes' ]; then
 
     # Configuring MySQL/MariaDB
     wget $vestacp/mysql/$mycnf -O /etc/mysql/my.cnf
-    mysql_install_db
+    if [ "$release" != '16.04' ]; then
+        mysql_install_db
+    fi
     update-rc.d mysql defaults
     service mysql start
     check_result $? "mysql start failed"