[fix] failing Yarn test, false negative check result and artifact upload

[adoroszlai]

Yarn PI test is failing due to Hadoop version mismatch:

Running command 'yarn jar /opt/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.2.1.jar pi 10 10
${rc} = 255
${output} = JAR does not exist or is not a normal file: /opt/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.2.1.jar

but test workflow is still passing: https://github.com/adoroszlai/docker-hadoop/runs/7052394243#step:7:272 (same code as https://github.com/flokkr/docker-hadoop/runs/3089708518, but logs for that are no longer available).

Also, workflow does not upload test result due to mismatch of paths: No files were found with the provided path: test/result. No artifacts will be uploaded.

This PR has the following changes:

1. Ensure workflow fails in case of test error: https://github.com/adoroszlai/docker-hadoop/runs/7052540407#step:7:290
2. Fix test result path for artifact upload: https://github.com/adoroszlai/docker-hadoop/actions/runs/2559928513#artifacts
3. Fix failing test: https://github.com/adoroszlai/docker-hadoop/runs/7052615965#step:7:260

[adoroszlai]

@elek please review