Release Testing: Verify FLINK-28915 Support artifact fetching in Standalone and native K8s application mode

This ticket covers testing FLINK-28915. More details and the added docs are accessible on the PR

Test 1: Pass local:// job jar in standalone mode, check the artifacts are not actually copied.
Test 2: Pass multiple artifacts in standalone mode.
Test 3: Pass a non-local job jar in native k8s mode. [1]
Test 4: Pass additional remote artifacts in native k8s mode.

Available config options: https://nightlies.apache.org/flink/flink-docs-master/docs/deployment/config/#artifact-fetching

[1] Custom docker image build instructions: https://github.com/apache/flink-docker/tree/dev-master

Note: The docker build instructions also contains a web server example that can be used to serve HTTP artifacts.