Add illustration for the Agents view empty state

Purpose

As we are changing the Kubernetes section UX in gitlab#340759 (closed) we are adding a new illustration for the Agents view empty state.

This MR is a part of the revisiting the Kubernetes section issue that contains the following steps:

1. Move clusters empty state to Vue
2. Change the illustration for the agents empty state <-- \textcolor{#FC6D26}{\textsf{You are here}}
3. Change the navigation for the clusters based page
4. Change the copy in the existing components
5. Change the navigation on the clusters page to Vue and actions button on the top of the page (introducing the clusters_main_view and clusters_actions components
6. Add the 'All' tab

More information is in the main MR(gitlab!71482 (closed))

Screenshots

gitlab#254998[000__Kubernetes_integrations_-_All_tabs_Stacked_Cards.png]

Checklist

For a new icon and/or illustration:

• If this adds an icon ensure that it follows the new icon checklists.
• If this adds an illustration ensure that it follows the new illustration checklists.