This does a very minimal build without default devices or features. I
chose the aarch64 runner as it doesn't count towards CI minutes and is
a fairly under-utilised builder.

Message-Id: <20230503091244.1450613-20-alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>