Description of problem:

The valid domain name of  `platform.aws.hostedZone` should be <cluster-name>.<baseDomain> or <baseDomain>, otherwise the installer will generate invalid api endpoints, this will cause the bootstrap process to fail.

e.g.
base domain: qe.devcluster.openshift.com
domain name of `platform.aws.hostedZone`: pre-created-yunjiang-r53e-4639299.qe.devcluster.openshift.com

The records in private hosted zone will be like:
api.yunjiang-r53e.qe.devcluster.openshift.com.pre-created-yunjiang-r53e-4639299.qe.devcluster.openshift.com.
api-int.yunjiang-r53e.qe.devcluster.openshift.com.pre-created-yunjiang-r53e-4639299.qe.devcluster.openshift.com.

bootkube error:
Apr 26 02:10:58 ip-10-0-4-35 sudo[10173]: pam_unix(sudo:session): session opened for user root by (uid=0)
Apr 26 02:10:58 ip-10-0-4-35 sudo[10198]:     root : TTY=unknown ; PWD=/var/opt/openshift ; USER=root ; ENV=KUBECONFIG=/opt/openshift/auth/kubeconfig ; COMMAND=/bin/oc --request-timeout=5s get secrets --all-namespaces -o=custom-columns=NAMESPACE:.metadata.namespace,NAME:.metadata.name,TYPE:.type,ANNOTATIONS:.metadata.annotations
Apr 26 02:10:58 ip-10-0-4-35 sudo[10198]: pam_unix(sudo:session): session opened for user root by (uid=0)
Apr 26 02:10:58 ip-10-0-4-35 systemd[1]: bootkube.service: Main process exited, code=exited, status=1/FAILURE
Apr 26 02:10:58 ip-10-0-4-35 systemd[1]: bootkube.service: Failed with result 'exit-code'.
Apr 26 02:11:00 ip-10-0-4-35 bootkube.sh[2326]: Unable to connect to the server: dial tcp: lookup api-int.yunjiang-r53e.qe.devcluster.openshift.com on 10.0.0.2:53: no such host


How reproducible:
Always.

Steps to Reproduce:
1. Create a private hosted zone and associate with VPC.
domain name: pre-created-yunjiang-r53e-4639299.qe.devcluster.openshift.com
hosted zone id: Z05164533R1ZNB61TQ6QA

2. Create and update install-config:

apiVersion: v1
baseDomain: qe.devcluster.openshift.com
controlPlane:
  architecture: amd64
  hyperthreading: Enabled
  name: master
  platform: {}
  replicas: 3
compute:
- architecture: amd64
  hyperthreading: Enabled
  name: worker
  platform: {}
  replicas: 3
metadata:
  name: yunjiang-r53e
platform:
  aws:
    region: us-east-2
    subnets:
    - subnet-0cb8fd22ec8849782
    - subnet-09f8d13a9f6b8d0c3
    - subnet-022b879d8b45bdfd9
    - subnet-0bb1e820db022652a
    hostedZone: Z05164533R1ZNB61TQ6QA
pullSecret: HIDDEN
sshKey: HIDDEN
networking:
  clusterNetwork:
  - cidr: 10.128.0.0/14
    hostPrefix: 23
  serviceNetwork:
  - 172.30.0.0/16
  machineNetwork:
  - cidr: 10.0.0.0/16
  networkType: OpenShiftSDN
publish: External

3. Create cluster

Actual results:
Bootstrap process failed with the above errors.

Expected results:
installer does a pre-check, if the domain name of `platform.aws.hostedZone` is not <baseDomain> or <cluster-name>.<baseDomain>, it should report a fatal error and exit in the early stage, instead of getting failed in the bootstrap process.