[aws][edge-zones][CI][manifest-check] Prevent run 'mixed' and 'all' tests when region support single edge-zone

Goal:

• Limit the CI step "openshift-installer-manifests-aws-edge-zones"[1], introducedhere[2] for running "mixed" and "all" tests when the tested region has only one edge zone available. It will result in the same test of "single", so it can be skipped in this situation. Example of result[3], from installer PR.

References:

[1] https://github.com/openshift/release/pull/47996/files#diff-dc7efcf0961582639d156caa74bc5359d5664e5ecdb7fc89f871153deff30443 

https://github.com/openshift/release/pull/47996/files#diff-368d55264661af768b0d70152f1659a3a1369d58f44925076810f1a197272dc7R433-R436 

 [2] SPLAT-1448 https://github.com/openshift/release/pull/47996 

[3] https://prow.ci.openshift.org/view/gs/test-platform-results/pr-logs/pull/openshift_installer/7983/pull-ci-openshift-installer-master-e2e-aws-ovn-edge-zones-manifest-validation/1760367387036618752 

https://gcsweb-ci.apps.ci.l2s4.p1.openshiftapps.com/gcs/test-platform-results/pr-logs/pull/openshift_installer/7983/pull-ci-openshift-installer-master-e2e-aws-ovn-edge-zones-manifest-validation/1760367387036618752/artifacts/e2e-aws-ovn-edge-zones-manifest-validation/openshift-installer-manifests-aws-edge-zones/artifacts/