Merge branch 'hotfix/3859' into 'stable-3.1'

fixed #3859

Bug fix for #3859, adding `class="form-control"` makes the box full-width. Same like the refresh box here:
https://git.ispconfig.org/ispconfig/ispconfig3/blob/master/interface/web/monitor/templates/show_sys_state.htm#L10

See merge request !407

interface/web/monitor/lib/module.conf.php

@@ -38,7 +38,7 @@ $module["nav"][] = array( 'title' => 'System State (All Servers)',
 
 $servers = $app->db->queryAllRecords("SELECT server_id, server_name FROM server order by server_name");
 
-$dropDown = "<select id='server_id' onchange=\"ISPConfig.loadContent('monitor/show_sys_state.php?state=server&server=' + document.getElementById('server_id').value);\">";
+$dropDown = "<select id='server_id' onchange=\"ISPConfig.loadContent('monitor/show_sys_state.php?state=server&server=' + document.getElementById('server_id').value);\" class='form-control'>";
 foreach ($servers as $server)
 {
 	$dropDown .= "<option value='" . $server['server_id'] . "|" . $server['server_name'] . "'>" . $server['server_name'] . "</option>";