This is mostly to ensure we don't include the toolchain and bootstrap
builds in DOCKER_IMAGES which is useful when verifying all images
still build.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211026102234.3961636-10-alex.bennee@linaro.org>