[FLINK-21561] Predownload/Cache large E2E test artifacts

[autophagy]

What is the purpose of the change

This change aims to download and cache large E2E artifacts from archive.apache.org, to speed up subequent E2E tests. Instead of redownloading these files every time, they are downloaded to the e2e_artifact_cache folder and linked to where they are expected in the tests. Azure Pipelines will then cache these files, avoiding constant redownloading of hadoop, flink and confluent.

Brief change log

• E2E test scripts have been modified to persist/cache large artifacts used between tests.

Verifying this change

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (no)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not applicable)

[flinkbot]

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Automated Checks

Last check on commit 3f85a1b (Thu Mar 04 10:13:29 UTC 2021)

Warnings:

• No documentation files were touched! Remember to keep the Flink docs up to date!

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Review Progress

• ❓ 1. The [description] looks good.
• ❓ 2. There is [consensus] that the contribution should go into to Flink.
• ❓ 3. Needs [attention] from.
• ❓ 4. The change fits into the overall [architecture].
• ❓ 5. Overall code [quality] is good.

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CI report:

• 3f85a1b UNKNOWN
• 2394feb UNKNOWN
• d1e2a32 Azure: SUCCESS

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[zentol]

there's another wget usage in elasticsearch-common that we could adjust as well.

[autophagy]

@flinkbot run azure

[rmetzger]

pushing (even an empty commit) is a much more reliable way of triggering azure builds

[rmetzger]

I manually re-triggered the failed test, because it failed somewhere else: https://dev.azure.com/apache-flink/apache-flink/_build/results?buildId=14919&view=results

[rmetzger]

Thanks a lot for fixing this. Merging your PR now.