Update to RHOAI version 2.9

[mamurak]

The current content refers explicitly and implicitly to RHOAI version 2.8. With the new product release version 2.9, the following parts need to be updated:

• Product documentation reference in chapter 1 introduction.
• RHOAI does not have a dependency on OpenShift Pipelines anymore. Instead, it now requires prior installation of
  • OpenShift Service Mesh
  • OpenShift Serverless
  • Red Hat Authorino
• This affects:
  • General Information about Installation
  • Installing Dependencies Using the Web Console
  • Uninstalling Red Hat OpenShift AI
• The RHOAI dashboard UI has been redesigned, so the UI dashboard screenshots need to be updated in the following sections:
  • Installing Dependencies Using the Web Console
  • Users, Projects, and Permissions
  • Importing Custom Notebook Images