Tag Tracking+: Fix search dropdown mode

[marcustyphoon]

Description

After the "improved search typeahead" change (is this out to everyone?), the search dropdown doesn't contain every tracked tag, and clicking a button in the dropdown opens a new modal interface with all of one's tracked tags.

This honestly makes Tag Tracking+'s search-only mode feel kind of pointless, at least to me? Not sure if we should simply remove it (either the functionality in its entirety or just the mode selector). Would like to hear opinions on that.

Anyway, this makes the mode at least work. My CSS is a little odd? Not sure if it could be improved.

Testing steps