Downgrade oracle to 21 and ensure oracle instant client is version-locked

Adding updated oracle instant client RPMs to cta-ci-others causes all machines to upgrade the oracle version, as it is not properly version-locked. As such, we should remove the v23 RPMs from cta-ci-others to ensure existing machines can work fine. Using the versionlock, we should be able to continue with v21 for a while in development. Before we do the upgrade, we first need to have this versionlock in place in production.