Use Java 17 in docker

I propose that our Docker image for Solr 9 use Java 17, the latest LTS release of Java. A change like this ought to only occur on a major version, and hence I propose doing it now.

Dev list thread, "Propose Solr 9 Docker image use Java 17":
https://lists.apache.org/thread/rx490w221trqvxdzddv6tp2g411fxstk