ekncontent: Remove obsolete TODO
ekncontent: Remove obsolete TODO

When xapian-bridge was intended to be a general component for use with
Xapian, the query parser prefixes were intended to be configurable
instead of the hardcoded defaults used for knowledge app databases.
However, without xapian-bridge, the TODO makes no sense anymore.

https://phabricator.endlessm.com/T20373

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib