fix: ListApps now discovers plain k8s yaml containing directories (#8949)

[ashinsabu3]

closes https://github.com/argoproj/argo-cd/issues/8949 also closes https://github.com/argoproj/argo-cd/issues/13045 potentially

Checklist:

• [ ] Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• [ ] The title of the PR states what changed and the related issues number (used for the release note).
• [ ] The title of the PR conforms to the Toolchain Guide
• [ ] I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• [ ] I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• [ ] Does this PR require documentation updates?
• [ ] I've updated documentation as required by this PR.
• [ ] I have signed off all my commits as required by DCO
• [ ] I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• [ ] My build is green (troubleshooting builds).
• [ ] My new feature complies with the feature status guidelines.
• [x] I have added a brief description of why this PR is necessary and/or what this PR solves.
• [x] Optional. My organization is added to USERS.md.
• [ ] Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

[bunnyshell[bot]]

:white_check_mark: Preview Environment deployed on Bunnyshell

Component	Endpoints
argocd	https://argocd-qprp3u.bunnyenv.com/
argocd-ttyd	https://argocd-web-cli-qprp3u.bunnyenv.com/

See: Environment Details | Pipeline Logs

Available commands (reply to this comment):

• 🔴 /bns:stop to stop the environment
• :rocket: /bns:deploy to redeploy the environment
• :x: /bns:delete to remove the environment