Edited and reordered topics in Multi-project pipelines

What does this MR do?

Changing the workflow and trying to pare down the language.

A few other notes:

• I removed the PREMIUM tag from the intro paragraph because as long as the topic itself has a tier badge, that should be sufficient.
• I tried to make it more workflow-based, so I moved the Multi-project visualization topic down.
• This text is listed twice so I removed one instance of it: In the example, staging is marked as successful as soon as a downstream pipeline gets created.

Related issues

Related to: #327171 (closed)

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