ADX-1088 Change default webpack mode to production.

[tomeksabala]

Description

Changing webpack mode to production should greatly (6x) decrease the size of our JS components.

Checklist

Put an x in the boxes that apply to this pull request (you can also fill these out after opening the pull request).
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• The Jira ticket for this issue has been updated to "Ready to Review" or equivalent.
• I have developed these changes in discussion with the appropriate project manager.
• My code follows the general Fjelltopp documentation (see Confluence).
• I have made corresponding changes to the Fjelltopp documentation (see Confluence).
• I have rebased this branch with master.
• New dependency changes have been committed.
• I have added automated tests that prove my fix is effective or that my feature works.
• New and existing tests pass locally with my changes.
• My changes generate no new warnings.
• I have performed a self-review of my own code.
• I have assigned at least one reviewer.