metadata blocks are not hidden when dataverseAlias is specified in tsv

At https://guides.dataverse.org/en/6.8/admin/metadatacustomization.html#metadatablock-properties we document a property called dataverseAlias that should have this effect:

"If specified, this metadata block will be available only to the Dataverse collection designated here by its alias and to children of that Dataverse collection."

For example, the SAEF metadata block uses dataverseAlias=SAEF: https://github.com/IQSS/dataverse.harvard.edu/blob/96a97bfdfc97773cc58075e54252b4caca3b98e5/metadatablocks/customSAEF.tsv

This results in the SAEF block being hidden (along with many others) in JSF:

However, in the SPA, dataverseAlias (which translates to owner_id in the database) is not respected. All blocks are shown:

See also discussion at https://dataverse.zulipchat.com/#narrow/channel/378866-troubleshooting/topic/Installing.20metadata.20block.20-.20it's.20not.20showing.20up/near/544990351

Start by tracing the SPA entry point that loads and displays metadata blocks, then compare its filtering with the documented dataverseAlias behavior and the SAEF example in customSAEF.tsv. Check how owner_id is represented in the returned data. Done means blocks scoped to a Dataverse alias are shown only there and in its children, matching JSF behavior.