Category Tree: Reduce number of categories

Don't use variable to set category, plugin gallery build script needs the pure string..

plugins/mysql/mysql_report

@@ -54,7 +54,6 @@ mysqlbin=$(which mysql)
 
 default_errorvalue=30
 default_title="Results from MySQL queries"
-default_category="mysql"
 default_vlabel="value / sec"
 default_info="This graph shows results of one or more SQL queries."
 default_args="--base 1000 -l 0"
@@ -77,7 +76,6 @@ fi
 
 [ -n "${errorvalue}" ] || errorvalue=${default_errorvalue}
 [ -n "${title}" ] || title="${default_title}"
-[ -n "${category}" ] || category="${default_category}"
 [ -n "${vlabel}" ] || vlabel="${default_vlabel}"
 [ -n "${info}" ] || info="${default_info}"
 [ -n "${args}" ] || args="${default_args}"
@@ -89,7 +87,7 @@ graph_title ${title}
 graph_args ${args}
 graph_scale ${scale}
 graph_vlabel ${vlabel}
-graph_category ${category}
+graph_category db
 graph_info ${info}
 EOH1
   [ -n "${period}" ] && echo "graph_period ${period}"