3.x: Update Dockerfiles

[barchetta]

This PR:

1. Removes Dockerfiles from some examples to simplify maintenance and improve consistency. Dockerfiles are still included in the quickstarts
2. Update Dockerfiles to use jdk-no-fee-term from container-registry.oracle.com instead of openjdk.
3. Updates base linux image to container-registry.oracle.com/os/oraclelinux:9-slim

Why jdk-no-fee-term?

1. openjdk stops getting updates after the next version of the JDK is released. jdk-no-fee-term gets updates until one year after the next LTS version (so much longer)
2. Like the openjdk repo, no login is needed. So user experience should not be impacted.

Tip: if for some reason you run into authentication errors with container-registry.oracle.com (even when accessing repositories that should not require authentication) it might be caused by cached expired credentials mucking up the works. Try this:

docker logout container-registry.oracle.com
rm ~/.docker/config.json