The chevron sometime can be confused as an icon for expanding the
stream topics especially for the new users.
This commit replaces the confusing chevron icon from the stream-sidebar,
topic-list, user-presence-row, all-messages and starred-messages with
ellipsis-v icon(vertical three dots).
Fixes: #7115
The only place we ever set active-sub-filter is
right after we build the template, so there is
no reason to have it be a separate step.
(I made a similar fix to pm_list recently, and
this helps set the stage for doing vdom-like
stuff.)
