Remove javadocs from releases (except for publishing) [LUCENE-6257]

In #7309, one idea discussed to decrease the size of release artifacts was to remove javadocs from the binary release. Anyone needing javadocs offline can download the source distribution and generate the javadocs.

I also think we should investigate removing javadocs jars from maven. I did a quick test, and getting the source in intellij seemed sufficient to show javadocs. However, this test was far from scientific, so if someone knows for sure whether a separate javadocs jar is truly necessary, please say so.

Regardless of the outcome of the two ideas above, we would continue building, validating and making the javadocs available online.



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Migrated from [LUCENE-6257](https://issues.apache.org/jira/browse/LUCENE-6257) by Ryan Ernst (@rjernst), updated Oct 31 2019
Attachments: [screenshot-1.png](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-6257/screenshot-1.png), [screenshot-2.png](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-6257/screenshot-2.png)

Start by reviewing how binary releases, source distributions, Maven artifacts, and online javadocs are built and published. Determine whether removing javadocs from binary and Maven releases is safe while retaining online publication; done means the artifact policy is decided and the relevant release outputs and validation still work.

Written by the indexing model from the issue text.