RCFilters UI: Unify li bullets with and without highlights

RCFilters UI: Unify li bullets with and without highlights

Make sure that the placement of the texts under the bullets is
the same whether the highlight is on or off. Otherwise, the list
is shifting a bit to the right to make room for highlight 'bullets'
when we press the highlight key.

Bonus: Make sure the highlight container is only appended to each
bullet once, even if the process is called for more than once on
the same content.

Bug: T163275
Bug: T163387
Change-Id: I4c2cf6176d5129dd2bc37d2f58ed84e85aca8560