Add support for Elasticsearch version 7.3.*

Upgrade elasticsearch-rest-client to 7.3.0.

Add V7_3 to the version manager, and use this in all the V7 tests.

Use the 7.3.0 image from blacktop in the test container.

Bug: Issue 11267
Change-Id: Id65e4d86238101e180dc8adf6b63ad7c53efe190
8 files changed
tree: a3a902f10679cb9b8e65f9ed4eba60ec11dc9f24
  1. gerrit-acceptance-tests/
  2. gerrit-elasticsearch/
  3. gerrit-pgm/