Change script retrieval away from git

Rely on a simpler wget method to get the test script

Signed-off-by: Louis Bouchard <louis.bouchard@canonical.com>
Remove default/kdump-tools setup from cloud-config

This is now done by the test script itself

Signed-off-by: Louis Bouchard <louis.bouchard@canonical.com>
Load kdump after setting up default/kdump-tools

Slight wait time is needed or the module cannot load before the
forced crash

Signed-off-by: Louis Bouchard <louis.bouchard@canonical.com>