## Why
Selected executor plugin roots could still expose capabilities when managed
requirements disabled the `plugins` feature.
## What changed
- Suppress MCP servers, skills, apps, and connectors from selected executor
plugins when `plugins` is disabled, while preserving the selected-root
identity used to filter those capabilities.
- Apply the policy consistently to direct selected-root discovery and batched
executor capability discovery.
## Testing
- Add contributor-level and app-server coverage that verifies disabled plugin
capabilities are absent and their MCP servers never start.
GitOrigin-RevId: e30bd8a936c4b0e083908b89a65f4d02e01747de