[Task](greenhouse): Remove legacy admin applications and cleanup dependencies

[ArtieReus]

Task Description

Clean up the greenhouse codebase by removing legacy admin applications and optimizing package dependencies to reduce bundle size and maintenance overhead.

Sub-tasks

1. Remove Legacy Admin Plugins

• Remove legacy teams plugin code from apps/greenhouse
• Remove legacy secrets plugin code from apps/greenhouse
• Clean up routes and navigation references to teams/secrets plugins
• Remove related components, pages, and configurations
• Update documentation to reflect the removal
• Verify no breaking changes to current functionality

2. Cleanup Package Dependencies

• Audit package.json for unused dependencies (like lodash will be not anymore needed)
• Remove dependencies specific to teams/secrets plugins
• Ensure all functionality still works after cleanup

Related Issues

Additional Context

• [EPIC](greenhouse): Admin Area - plugin presets development (2) #1396

[guoda-puidokaite]

(Update) Addressing next sprint after confirming new dashboard working as expected

[guoda-puidokaite]

Other prios, moving forward