Add panel flyout does not load panel types

[eokoneyo]

Kibana version:

main

Describe the bug:

Opening the the add panel flyout as soon as the dashboard page loads or when the network is slow results in a flyout panel with no panels available

Steps to reproduce:

Slow down your network speed, refresh your dashboard, and click on the “Add panel” button as soon as it is available (before the panels have a chance to load). You see “No panel types found” and they don’t load until you close and re-open the flyout

Expected behavior:
Panel types are rendered when the flyout is open for the user.

Screenshots (if relevant):

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)