Try to reenable functional test in docker

We try to reenable the functional test in docker. To start, let's try to run example_functional in docker. If it works, then move it to sanity.external.

https://github.com/adoptium/aqa-tests/blob/master/external/functional-test/playlist.xml#L43C17-L43C35

Start with external/functional-test/playlist.xml at the referenced line and inspect the example_functional entry. Run example_functional in Docker first, then verify whether it can be moved to sanity.external. Done means the functional test runs successfully in Docker and is enabled in the requested location.

Written by the indexing model from the issue text.