fix: stop argo-cd secret reseting admin password when updated using cli/dashboard

[anandrkskd]

What type of PR is this?
/kind bug

What does this PR do / why we need it:
This PR fixes the reset of Argo-cd admin password when updated using cli/dashboard. Argo-cd will reset the password when the data field for admin.password is nil.

Have you updated the necessary documentation?

• Documentation update is required by this PR.
• Documentation has been updated.

Which issue(s) this PR fixes:

Fixes GITOPS-3581

How to test changes / Special notes to the reviewer:

To check it locally, running k8s cluster

1. Run below command

make install run

2. On different terminal run

kubectl port-forward service/example-argocd-server 8443:443

3. Get login password and perform login

kubectl -n argocd get secret <secret-name> -o jsonpath="{.data.password}" | base64 -d; echo
argocd login --username admin --password <password>  127.0.0.1:8080

4. Update password

$ argocd account update-password
*** Enter password of currently logged in user (admin):
*** Enter new password for user admin:
*** Confirm new password for user admin:

5. Login using new password
   argocd login --username admin --password <NewPassword> 127.0.0.1:8080

[svghadi]

LGTM. Thanks @anandrkskd

[jaideepr97]

LGTM

[svghadi]

/cherry-pick release-0.9