fix: revert type of status.upgradedPostgresVersion to string

[kurokobo]

SUMMARY

Closes #1738

As follow-up for #1741, this PR changes to store status.upgradedPostgresVersion as a string, to keep backward compatibility.

ISSUE TYPE

• Bug, Docs Fix or other nominal change

ADDITIONAL INFORMATION

Tested by following reproducible steps in #1738 (comment).

In step 7, deploy customized Operator with this PR instead of devel image:

$ IMG=registry.example.com/ansible/awx-operator:pg make docker-build docker-push deploy

In step 8, I can confirm there is no failed task.

$ kubectl -n awx logs deployments/awx-operator-controller-manager | grep -e "^PLAY RECAP" -A 1
PLAY RECAP *********************************************************************
localhost                  : ok=112  changed=16   unreachable=0    failed=0    skipped=75   rescued=0    ignored=1   
--
PLAY RECAP *********************************************************************
localhost                  : ok=85   changed=1    unreachable=0    failed=0    skipped=83   rescued=0    ignored=1 

In step 10. I can confirm PSQL 15 is running.

$ kubectl -n awx get pod
NAME                                              READY   STATUS    RESTARTS   AGE
awx-operator-controller-manager-984cd5d6f-jqwgw   2/2     Running   0          4m43s
awx-demo-postgres-15-0                            1/1     Running   0          3m50s
awx-demo-task-57d668d7b5-bmjrv                    4/4     Running   0          3m19s
awx-demo-web-6777767f5b-6lcwt                     3/3     Running   0          3m18s

In step 11, the status has upgradedPostgresVersion.

$ kubectl -n awx get awx awx-demo -o yaml
...
status:
  adminPasswordSecret: awx-demo-admin-password
  adminUser: admin
  broadcastWebsocketSecret: awx-demo-broadcast-websocket
  conditions:
  - lastTransitionTime: "2024-03-03T16:24:35Z"
    reason: ""
    status: "False"
    type: Failure
  - lastTransitionTime: "2024-03-03T16:21:12Z"
    reason: Successful
    status: "True"
    type: Running
  - lastTransitionTime: "2024-03-03T16:28:51Z"
    reason: Successful
    status: "True"
    type: Successful
  image: quay.io/ansible/awx:latest
  postgresConfigurationSecret: awx-demo-postgres-configuration
  secretKeySecret: awx-demo-secret-key
  upgradedPostgresVersion: "15"
  version: 23.9.0

In addition, just to be sure, I restarted Operator to trigger new reconciliation loop for existing AWX that has upgradedPostgresVersion and verified that the loop completes without any errors.