selftests: Replace sleep with slowwait

Replace the sleep in kill_procs with slowwait.

Signed-off-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250910025828.38900-2-dsahern@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
1 file changed