Remove references to GUCs that are no longer present

[hanefi]

Why are we implementing it? (sales eng)

We removed some GUCs in the past, and we still keep references to them in the docs. Recently it caused some confusion among team members.

• citus.binary_worker_copy_format - not present on >= 11.1.0
• citus.multi_shard_commit_protocol - not present on >= 11.0.0_beta
• citus.shard_max_size - not present on >= 11.0.0_beta

What are the typical use cases?

Communication goals (e.g. detailed howto vs orientation)

Good locations for content in docs structure

Check all occurences of these GUCS and remove all references. Some of the changes may require understanding how the behavior changed after we removed these GUCs.

How does this work? (devs)

Example sql

Corner cases, gotchas

It is not only the latest version of Citus that is affected. We should backport some of the commits to earlier versions as well.

Are there relevant blog posts or outside documentation about the concept/feature?

Link to relevant commits and regression tests if applicable