feature/pdct-1540-set-all-metadata-entries-to-a-string-type

[odrakes-cpr]

What's changed?

fix: ensure all metadata values are list of strings

• vespa expects these values to be strings, if any other type is provided the ingest will fail

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[linear]

PDCT-1540 Set all metadata entries to a string type

[diversemix]

Looking good