src/assets/i18n: update Finnish language strings

[alanorth]

Description

Contributed by Reeta Kuukoski from the National Library of Finland. Consolidated from previous pull request:

• A set of new Finnish translation keys #2342

Instructions for Reviewers

List of changes in this PR:

• Updated Finnish language strings

Include guidance for how to test or review your PR.
Build the Angular UI and check to make sure the Finnish UI strings load and display properly.

Checklist

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[tdonohue]

👍 Thanks @reetagithub and @alanorth ! Gave this a quick test and the new Finnish translations look to be visible in the UI.

[dspace-bot]

Successfully created backport PR for main:

• [Port main] src/assets/i18n: update Finnish language strings #2417