chore: transmit only app manifests to the cmp-server for plugin-based applications

[jsolana]

Closes https://github.com/argoproj/argo-cd/issues/17951

Transmit only the necessary information to the cmp-server to improve the performance. More info here

As a quick win, transmit only appPath manifests for plugin-based applications.

Checklist:

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[crenshaw-dev]

I think a better implementation would be to respect the manifest-generate-paths annotation.

This implementation would break some apps where manifests reference resources outside the app path.