[FLINK-35516][Connector/Files] Update the Experimental annotation for files connector

[RocMarshal]

What is the purpose of the change

Update the Experimental annotation for files connector

Brief change log

Update the Experimental annotation for files connector

Verifying this change

This change is already covered by 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, 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]

CI report:

• 11ff6f8ba3f469c7209b472c4b5385f9edab37ba Azure: FAILURE

Bot commands

The @flinkbot bot supports the following commands:

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

[github-actions[bot]]

This PR is being marked as stale since it has not had any activity in the last 90 days. If you would like to keep this PR alive, please leave a comment asking for a review. If the PR has merge conflicts, update it with the latest from the base branch.

If you are having difficulty finding a reviewer, please reach out to the community, contact details can be found here: https://flink.apache.org/what-is-flink/community/

If this PR is no longer valid or desired, please feel free to close it. If no activity occurs in the next 30 days, it will be automatically closed.