cache-domains: added pre-test.sh CI step

cache-domains: added pre-test.sh CI step

Some packages variants have conflicting dependencies with the
base packages and the CI test will fail to install before anything
can be done by the packages to setup the system for install.

This change adds a pre-test.sh that runs before the install so things
like the default libustream variant can be swapped out as shown in the
updated cache-domains.

Signed-off-by: Gerard Ryan <G.M0N3Y.2503@gmail.com>
(cherry picked from commit 61997c86b01c83320a2cbb1b490941a8af741253)