Remove local definitions for global USE=vala and USE=introspeciton

Remove local definitions for global USE=vala and USE=introspeciton

23 packages had local use definitions that matched up perfectly with
the global definitions. Remove them as they're not necessary. This
is a metadata only change.

Closes: https://github.com/gentoo/gentoo/pull/1100

Acked-by: Justin Lecher <jlec@gentoo.org>
Signed-off-by: Patrice Clement <monsieurp@gentoo.org>