Fix Additional XSS Vulnerability In "tpl.inc.php"

@protich @greezybacon in regards to https://github.com/osTicket/osTicket-1.8/pull/1162. My apologies, during initial testing I only noticed the value being output unsanitized in the `<input>` field using the provided POC. However, the attack is also possible via the `<textarea>` field using:

```
/scp/templates.php?tpl_id=1&a=implement&code_name="></textarea><script>alert(1)</script>
```
Sorry! It was a tiring day, I should have investigated further. =o(