Add support for Elasticsearch version 7.9.*

Upgrade elasticsearch-rest-client to 7.9.3, which is the currently
latest 7.9 minor version available.

Add V7_9 to the version manager and use it for all the V7 tests.

Change-Id: I7d76ece60d3ed7400bcf28bcd45d0e2e02870ccd
9 files changed
tree: edca6c06e9bdf7bba6d40ad594e2444256fec0b6
  1. java/
  2. javatests/