[dark-data-agent-chat] Duplicated role requirements in Dataplex Service Account instructions

[Yash55-max]

Steps to Reproduce

1. Navigate to the Turn Dark Data into Structured Gold codelab.
2. Go to section 5. Permissions Setup.
3. Scroll down to step 2. Grant Dataplex Service Account permissions to access the Cloud Storage Bucket.
4. Look at the bulleted list under Grant the following roles to this Service Account.

Expected Result

A clean list of unique roles required for the service account configuration.

Actual Result

The documentation lists a total of 10 items, repeating the same 3-4 storage roles multiple times and including malformed concatenated role strings (e.g., roles/dataplex.discoveryBigLakePublishingServiceAgentroles/storage.objectUser).