UI banner empty when permanent and no explicate bannerposition

[igaskin]

Checklist:

• I've searched in the docs and FAQ for my answer: https://bit.ly/argocd-faq.
• I've included steps to reproduce the bug.
• I've pasted the output of argocd version.

Describe the bug
The optional UI banner does not appear if there is no explicate value set for ui.bannerposition.

Possibly related to this PR: #14623

To Reproduce
Set the following in the argocd-cm

does work

data:
  ui.bannercontent: reproduce banner bug
  ui.bannerpermanent: "true"
  ui.bannerposition: top  

does not work

data:
  ui.bannercontent: reproduce banner bug
  ui.bannerpermanent: "true"

Expected behavior

Screenshots

Version

argocd version
argocd: v2.6.3+e05298b.dirty
  BuildDate: 2023-02-27T15:43:43Z
  GitCommit: e05298b9c6ab8610104271fa8491f019fee3c587
  GitTreeState: dirty
  GoVersion: go1.20.1
  Compiler: gc
  Platform: darwin/arm64
argocd-server: v2.10.0-rc1+d919606
  BuildDate: 2023-12-18T20:45:12Z
  GitCommit: d9196060c2d8ea3eadafe278900e776760c5fcc6
  GitTreeState: clean
  GoVersion: go1.21.3
  Compiler: gc
  Platform: linux/arm64
  Kustomize Version: v5.2.1 2023-10-19T20:13:51Z
  Helm Version: v3.13.2+g2a2fb3b
  Kubectl Version: v0.26.11
  Jsonnet Version: v0.20.0

Logs

Paste any relevant application logs here.

[keithchong]

This appears to be a regression. In the sample config here, the default behavior was such that if the bannerposition was not specified, the content would appear in the the banner at the top of the page.