IQSS/11095- Account for multivalue needed by cvoc scripts

[qqmyers]

What this PR does / why we need it: This PR changes the /api/admin/index/solr/schema output to correctly indicate that a field should be multivalued when it is the term-uri field of an external controlled vocabulary config. (Note the format of the output/etc. is not changed, just the content - same as if a metadatablock were editing to make a field multivalued.)

Which issue(s) this PR closes:

• Closes External CVoc - indexing can fail for single valued fields #11095

Special notes for your reviewer:

Suggestions on how to test this: Configure the ORCID script on the depositor field as described in the issue, test that indexing doesn't work now, works after the update and updating the solr schema/restarting solr.

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

Is there a release notes update needed for this change?: included

Additional documentation:

[coveralls]

coverage: 22.691% (+0.1%) from 22.571%
when pulling 968dfda on QualitativeDataRepository:IQSS/11095-fix-extcvoc-indexing
into a4d0127 on IQSS:develop.

[pdurbin]

I haven't run the code but I assume this is a no-op if a developer were to recreate the schema.xml file using the process I'm suggesting developers follow in this pull request (please take a look):

• Format Solr schema.xml using update-fields.sh on Linux #11024

That is, it's a no-op because we don't ship any sort of cvoc config out of the box. It's a feature that installations opt-in to.

I'm almost ready to send this to QA (test are passing: https://jenkins.dataverse.org/job/IQSS-Dataverse-Develop-PR/job/PR-11096/1/testReport/ ) but I did leave a few tiny suggestions.

[qqmyers]

Yes it's a no-op, but if Dataverse ever does ship with some external cvoc scripts registered, the right thing to do would be to run update-fields.sh on an instance with those scripts configured - so consistent with #11024.