tests: Rename domaincapsschemadata/ -> domaincapsdata/

tests: Rename domaincapsschemadata/ -> domaincapsdata/

The usual convention is to use ${foo}test.c for the test program
itself and either ${foo}data/ or ${foo}outdata/, depending on
whether it contains both input and output files or only the latter,
for the corresponding data directory.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>