Switch all welcome pages to use EmptyStatePattern component
Currently, each page uses a different erb template to display its content. By changing all these pages to mount the EmptyStatePattern component, we can have a unified look and feel and implement changes to the design in one central location.
Refs #32070 - Remove Puppet Environment react component
These components are no longer used after puppet has been extracted.
This is implemented in https://github.com/theforeman/foreman_puppet/pull/163