Changed the default value for OPENSHIFT_INSTALL_AWS_PUBLIC_ONLY to true

Author: Hector Vido

ci-operator/step-registry/ipi/install/install/ipi-install-install-ref.yaml

@@ -56,7 +56,7 @@ ref:
     default: "false"
     documentation:  "Use AWS Spot Instances for *master* nodes. Set to 'true' to opt into spot instances. Explicitly set to 'false' to opt out. Leave unset for the default, which may change. Note that spot masters are only supported when installing with a) CAPI; or b) newer installer versions (see https://github.com/openshift/installer/pull/8349). A preflight check will fail if this variable is set to 'true' for an unsupported configuration."
   - name: OPENSHIFT_INSTALL_AWS_PUBLIC_ONLY
-    default: ""
+    default: "true"
     documentation: "Whether to use only public subnets for AWS. Implies no NAT Gateways. Requires a VPC to be configured prior to install."
   dependencies:
   - name: "release:latest"