[ticket/13100] Display only confirmation buttons when deleting shadow topic

PHPBB3-13100
[ticket/13100] Remove pointless variable

PHPBB3-13100
Merge pull request #3044 from Elsensee/ticket/13100

[ticket/13100] Display only confirmation buttons when deleting shadow topic
Merge branch 'develop-ascraeus' into develop

Conflicts:
	phpBB/styles/subsilver2/template/confirm_delete_body.html