Remove last traces of KFileMetaDataWidget from information panel

Summary:
The whole information panel is not included when Baloo is not found,
so there is no need for the HAVE_BALOO guards.
KFileMetaDataWidget and KFileMetaDataConfigurationWidget were never part
of KF5, see https://git.reviewboard.kde.org/r/113153/

Test Plan: ctest

Reviewers: Frameworks, apol, ngraham, Dolphin, elvisangelaccio

Reviewed By: Dolphin, elvisangelaccio

Subscribers: elvisangelaccio, kfm-devel

Tags: Dolphin

Differential Revision: https://phabricator.kde.org/D20513