TT#76206 fix call teardown for half established dialogues
In case of an offer with a via-branch followed by a delete without a
via-branch (cancelled call), the call erroneously remains open after
deleting one half of the call. The reason is that un-answered branches
do not appear in the `other_tags` list and so are left out from being
checked.
Change-Id: Ib008f32ef5ee06a7ca997c900c9a3adc85b0f10d
(cherry picked from commit 55d4ccc50a)