GH-4779: Un-deprecate RDFa parser setting

[edwardsph]

GitHub issue resolved: #4779

Briefly describe the changes proposed in this PR:

PR #4858 reinstated some settings needed for RDFa support but I missed one that is used internally by the Semargl library. This PR removes the deprecation of VOCAB_EXPANSION_ENABLED so that 3rd party libraries which depend on it can work with RDF4J v5.

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PR Author Checklist (see the contributor guidelines for more details):

• my pull request is self-contained
• I've added tests for the changes I made - N/A
• I've applied code formatting (you can use mvn process-resources to format from the command line)
• I've squashed my commits where necessary
• every commit message starts with the issue number (GH-xxxx) followed by a meaningful description of the change

[hmottestad]

Thanks @edwardsph :)

This will be included in 5.0.1!