[FileMetaDataProvider] Only initialize KFormat where it actually used

Summary:
KFormat is only used in some code paths, move the instances to the
appropriate scopes.

Test Plan:
ctest passes
no functional changes

Reviewers: #baloo, #dolphin, nicolasfella, astippich, ngraham, elvisangelaccio

Reviewed By: astippich

Tags: #baloo

Differential Revision: https://phabricator.kde.org/D20909