docs: update nightlies page with latest state of nightlies

[amoeba]

What feature or improvement would you like to see?

https://arrow.apache.org/adbc/current/development/nightly.html seems out of date. We should update it:

• C++ nightlies are no longer being published to the arrow-adbc-nightlies channel. Should we drop this or re-establish nightlies on conda-forge?
• We should list the Node.js packages

[lidavidm]

Java packages too, right?

[amoeba]

What change would you make to the Java section of the nightlies page?

[lidavidm]

Ah, I was remembering the old page that didn't have a Java section. The new page seems fine.