[FLINK-30180][docs] Remove the description of Filesystem supporting for the lookup in the Supported Connectors section

[YesOrNo828]

What is the purpose of the change

In the Supported Connectors section, the graph shows that the Filesystem connector supports the lookup source. Actually, it doesn't.

So I want to remove this description.

Brief change log

• The documentation in the Supported Connectors section.

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

Documentation

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

[flinkbot]

CI report:

• c5fb448 Azure: SUCCESS
• aa36562 Azure: PENDING

Bot commands

The @flinkbot bot supports the following commands:

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

[MartijnVisser]

@YesOrNo828 Thanks for the PR, can you also change the Chinese documentation page on this?

[YesOrNo828]

Hi @MartijnVisser, Done with the Chinese documentation. Please have a look.

[MartijnVisser]

@YesOrNo828 Thanks, LGTM