[FLINK-34324][test] Makes all s3 related operations being declared and called in a single location

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What is the purpose of the change

• Fixes error message in test execution
• unifies S3-related code in one location

Brief change log

• Moves the entire s3-related logic into the if block

Verifying this change

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, 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]

CI report:

• b269e4f5086d47af9f9e5b787c1c32d0afce85dc Azure: FAILURE

Bot commands

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

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@flinkbot run azure

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Closing this one becaue there are still issues.