[client] Remove unnecessary references to Ray Client

[richardliaw]

Description

We reference Ray Client in a variety of places in our examples and documentation.

We should remove any extra references to Ray client, except for where the Ray Client documentation is.

So this includes but is not limited to:

• All Tune examples
• All train examples
• Documentation for all Libraries
• Ray.init entrypoint message
• Modin docs on the Ray repo

We can keep Ray Client for Workflows and the clusters section.

We will open a separate issue for improving the Ray Client (mentioning when and where we should use Ray Client).

Link

See these queries: Link and Doc Link

Sub-tasks

• [client][ml] Remove Ray Client references from Libraries Documentation and Examples #31621
• [Core] ray client docs clean up #31785