Operator doesn't reconcile on deletion of SA from repo setting

Description of problem:

When we create an argocd instance in a particular namespace, repo server has default as the default service account. If a user adds a new service account in argocd cr, it gets reflected in the repo server deployment. But while deleting the serviceaccount field from argocd cr repo setting, operator does not reconcile and the user might end up having a service account in repo server deployment that might not even be existing.

Issue: https://issues.redhat.com/browse/GITOPS-1873 

Workaround:

User can manually change the settings to have default serviceaccount in argocd cr instead of deleting 

Prerequisites (if any, like setup, operators/versions):

Openshift GitOps operator installed on the cluster  

Steps to Reproduce

1. Add a service account in spec.repo.serviceaccount in argocd cr (other than default)
2. Observe repo-server deployment reflecting new service account in serviceAccountName and serviceAccount fields 
3. Delete spec.repo.serviceaccount field in arocd cr

Actual results:

repo server deployment does not reconcile with new changes 

Expected results:

Overwrite the previous service account with default service account once it is deleted from spec.repo.serviceaccount in argocd cr

Reproducibility (Always/Intermittent/Only Once):

Always

Build Details:

v1.7.0- Build 22

Index image v4.8: registry-proxy.engineering.redhat.com/rh-osbs/iib:382889
Index image v4.9: registry-proxy.engineering.redhat.com/rh-osbs/iib:382894
Index image v4.10: registry-proxy.engineering.redhat.com/rh-osbs/iib:382899
Index image v4.11: registry-proxy.engineering.redhat.com/rh-osbs/iib:382903
Index image v4.12: registry-proxy.engineering.redhat.com/rh-osbs/iib:382908

Additional info (Such as Logs, Screenshots, etc):{}