ZOOKEEPER-5067 Remove older docs picker from the docs page

[yuriipalam]

We need to remove the "Older docs" picker from the docs page to avoid outdated lists on released docs pages.

For instance, if we release 3.9.10, 3.10.0, etc.
The docs built for 3.9.10 will have list of "Older docs" starting from 3.9.5, but 3.9.10 is already an older version in this case. The landing page should remain the source of truth for all the doc pages.

I also added a line to remove "docs-images" from the website built, since they are only consumed by the docs pages.

[anmolnar]

Duplicated by #2423

I still don't understand why would we need this patch. We expose the active releases docs pages in the menu, but we also need to provide access for older documentation somehow. If we remove the menu item, how could anyone find them?

[yuriipalam]

Duplicated by #2423

I still don't understand why would we need this patch. We expose the active releases docs pages in the menu, but we also need to provide access for older documentation somehow. If we remove the menu item, how could anyone find them?

Didn't know it's a duplicate.

I removed this older docs picker only from the documentation page(s), not from the navbar. It stays in the navbar and remains the source of truth.

[anmolnar]

lgtm. Thanks for the clarification!