## What changes were proposed in this pull request?

Move flume behind a profile, take 2. See https://github.com/apache/spark/pull/19365 for most of the back-story.

This change should fix the problem by removing the examples module dependency and moving Flume examples to the module itself. It also adds deprecation messages, per a discussion on dev about deprecating for 2.3.0.

## How was this patch tested?

Existing tests, which still enable flume integration.

Author: Sean Owen <sowen@cloudera.com>

Closes #19412 from srowen/SPARK-22142.2.