Branch page: Announcement topics should be always displayed on top of the branch

Steps for reproduce:
1. Create topic1 marked as announcement
2. Create topic2 marked as announcement and sticked
3. Create topic3 marked as sticked
4. Create topic4, without any marks

Actual result:
Topics are displayed in the following order

• Sticked topics ordered by last post date desc
• Other topics orded by last post date desc (including announcements)

See attached screenshot

Expected result:
Topics are displayed in the following order

• Announcement topics ordered by last post date desc
• Sticked topics ordered by last post date desc
• Other topics orded by last post date desc

See red figures on attached screenshot

Additional:

• See attached screenshot with the same branch on old javatalks.ru and on JCommune
• Also on old javatalks.ru the announcements are displayed on every page of the branch (sticked only on the first one)