python3: Avoid installing test data into recipe-sysroot

python3: Avoid installing test data into recipe-sysroot

There are several thousand files in the test directory which we don't need.
Adding these for the native and target sysroots is a crazy amount of files
to be throwing around needlessly. Delete the files from the sysroot side
of things to tidy up the sysroots and improve performance.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>