Table-header for a custom-component inside a repeatable group displays value instead of label.

### Description of the bug

The table-header for a custom-component inside a repeatable group displays value instead of label.
In the example below i would expect the label of the codelist-option to be displayed, but instead the value is displayed.


### Steps To Reproduce

1. Clone [this](https://altinn.studio/repos/dsb/uhell-transport-av-farlig-gods/pulls/1) repo and checkout the "custom_web_component" branch.
2. Start the app and navigate to "Varetype/produkt involvert"-page
3. Add a product to the repeatable group.

### Additional Information

[This issue](https://github.com/Altinn/app-frontend-react/issues/596) may be related.
[Relevant slack conversation](https://altinn.slack.com/archives/C02EJ9HKQA3/p1666964899209489)

Reproduce the issue by running the linked repository on the "custom_web_component" branch and navigating to the specified page. Trace the table-header rendering for a custom component in a repeatable group; done means the codelist option's label, rather than its value, is displayed.

Written by the indexing model from the issue text.