Badge notification text should not suggest that there may be a attachment when attachments are disabled

As raised in MDL-39923, the text included in badge notification e-mails includes at the bottom:

If there is no badge attached to this email, you can manage and download it from My badges page.

When e-mail attachments are disabled across Moodle, or for that Badge, this text should not be included in it's current form. It should simply state the latter half:

You can manage and download it from the My badges page.

(Additionally, it's missing the word 'the' in the existing text)