Removed unneeded OpenJDK install from docker images and updated Elastisearch to 7.17.8

[Zozman]

Summary

As described in the documentation for Elastisearch 7, the download of Elastisearch includes a bundled version of OpenJDK within the jdk directory of the download that Elastisearch recommends be used. Because of this, there is no need to manually install OpenJDK in the Docker images as Elastisearch not only already had it in the download (to see an example, download and uncompress https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.17.8-linux-x86_64.tar.gz) but is also set to use it by default. So this PR removes the Docker commands to perform this install as it's not needed, makes the container builds faster, and removes the burden of keeping the OpenJDK up to date from the Dockerfile.

In addition, also updated Elastisearch inside the Docker containers to 7.17.8 as updating this version to deal with https://www.cve.org/CVERecord?id=CVE-2021-44228 that's mentioned in #386 has never been done.

To Test

• To test the container in the docker_containers/mindmeld_docker directory, run docker-compose up --build from this directory.
• To test the container in the docker_containers/mindmeld_dep_docker directory, run docker-compose up --build from this directory.