Backport MIME database update to all branches

The change https://codereview.qt-project.org/c/qt/qtbase/+/575003 introduced the TIKA MIME type database instead of the one from freedesktop.org.

We need to make sure that this change is properly picked to all relevant branches, including 5.15 LTS.

Update: there is also a follow-up patch https://codereview.qt-project.org/c/qt/qtbase/+/575579 that is also required. Otherwise the unit-tests checking the old freedesktop.org database will fail the users will have no possibility to fall back to the freedesktop.org mimetype database even if they're fine with the licensing.