Cleanup idempotent entries from mimetype mapper table

Summary:
The OpenDocument and OfficeXML mime types are already covered by the
contains("document") statement, so no need to explicitly list these
for the Type::Document again.

Likewise for SVGs, which are already covered by the startswith("image/").

Reviewers: Baloo, Frameworks, ngraham, astippich, poboiko

Reviewed By: Baloo, ngraham

Subscribers: kde-frameworks-devel

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D19065