This is something that really needs to be fixed inside the content plugins you're using. In this case, it's the Phoca Gallery plugin. It has a forum and an issue tracker where you can report the issue.
In the meantime, you can override components/com_finder/tmpl/search/default_result.php
layout and add your customizations there. After this block:
if (!empty($this->result->summary) && !empty($this->result->body)) {
$full_description = Helper::parse($this->result->summary . $this->result->body);
}
Add this:
$full_description = preg_replace('/{.+}/', '', $full_description);
But beware this will strip any content between curly braces, not just valid shortcodes.