[FLINK-16400][fs] Fixing e2e tests that directly use Hadoop fs.

[AHeise]

What is the purpose of the change

Fixes two different kinds of errors caused by FLINK-16015, which disables direct access to Hadoop fs if we offer a plugin.

Brief change log

• Fixing YarnFileStageTestS3ITCase for direct Hadoop access by adding an exception in configuration.
• Removing filesystem kind. The need to differentiate between object storage and file system disappeared over the years. getKind() is now dead code.

Verifying this change

Fixes existing tests.

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

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

[flinkbot]

Thanks a lot for your contribution to the Apache Flink project. I'm the @flinkbot. I help the community
to review your pull request. We will use this comment to track the progress of the review.

Automated Checks

Last check on commit 59080ec (Wed Mar 04 15:44:21 UTC 2020)

Warnings:

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

_{Mention the bot in a comment to re-run the automated checks.}

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.

Please see the Pull Request Review Guide for a full explanation of the review process.

The Bot is tracking the review progress through labels. Labels are applied according to the order of the review items. For consensus, approval by a Flink committer of PMC member is required

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot approve description to approve one or more aspects (aspects: description, consensus, architecture and quality)
• @flinkbot approve all to approve all aspects
• @flinkbot approve-until architecture to approve everything until architecture
• @flinkbot attention @username1 [@username2 ..] to require somebody's attention
• @flinkbot disapprove architecture to remove an approval you gave earlier

[AHeise]

@StephanEwen , I did the rough thing and removed getKind completely. Could you double-check if this in your interest. I could also only remove the test and start deprecation.

[flinkbot]

CI report:

• 49cd498 Travis: SUCCESS Azure: FAILURE

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run travis re-run the last Travis build
• @flinkbot run azure re-run the last Azure build

[zentol]

The FileSystem class is a @Public API, meaning that no methods may be removed.

[StephanEwen]

If we cannot remove the method (@Public API), we could deprecate it, remove the tests, and open a ticket to remove it in the version after.

[AHeise]

There is still a test failure on azure (e2e) but it seems to be unrelated.

[pnowojski]

LGTM. I'm adding a one extra comment explaining why method is deprecated (it's not used anymore) and will merge in a minute.