The agent based workflow jobs introduced in https://github.com/openshift/release/pull/50293 run both the single arch payload and the multi-arch payload.

Acceptance Criteria:

• Agent jobs for s390x 4.17 and 4.18 use the multi-payload like the ppc64le jobs

• Agent jobs for s390x 4.17 and 4.18 that use the single arch payload are removed

Steps to Fix

• Ensure we're getting test runs that pass bootstrapping from the agent-remote-libvirt-multi-z-z jobs for 4.17 and 4.18.
• Delete these lines: https://github.com/openshift/release/blob/fc304850c4cffb2d1a988da489cfbb5ff3729c71/ci-operator/config/openshift/multiarch/openshift-multiarch-master__nightly-4.17.yaml#L444-L458
  Delete these lines: https://github.com/openshift/release/blob/fc304850c4cffb2d1a988da489cfbb5ff3729c71/ci-operator/config/openshift/multiarch/openshift-multiarch-master__nightly-4.18.yaml#L445-L460
• Run `$ make jobs`
• Create a pull request with those changes to openshift/release.