[FLINK-33589][docs] Fix connector_artifact to prevent generation of broken layout

[z3d1k]

What is the purpose of the change

Fix issue in connector_artifact shortcode causing generation of corrupted layout when used in combination with tabs.

Brief change log

Removed indentations fixing generation of corrupted doc layout.

Verifying this change

Can be verified by building the documentation locally.

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:

• 9a32cc9 Azure: SUCCESS

Bot commands

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

[dannycranmer]

LGTM