Change the recommended snmpwalk capture options to ease parsing. (#4804)

Remove `t` we lose the declaration of the Timeticks: type with that
Add `U` removes unit suffixes.
Add `b` displays indexes numerically instead of as strings

html/includes/output/capture.inc.php

@@ -39,7 +39,7 @@ switch ($type) {
     case 'snmpwalk':
         $device = device_by_name(mres($hostname));
 
-        $cmd = gen_snmpwalk_cmd($device, '.', ' -Onet');
+        $cmd = gen_snmpwalk_cmd($device, '.', ' -OUneb');
 
         if ($debug) {
             $cmd .= ' 2>&1';