Repeating group: Show table header when using components in table

### Description of the bug

The table headers in repeating groups are hidden when there is only one row and it is open for editing, this makes sense since there is no visible tabular data at this point. The exception to this is if you have components in the table, in that case you need the table headings since there is no other label for the input; this is not the case today.

There are also some weird empty rows with the edit container styling that sometimes occur when using only components in rows and no editcontainer


see: https://altinn.slack.com/archives/C02EVE4RU82/p1696503841696019

### Steps To Reproduce

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### Additional Information

_No response_

Start by reproducing the repeating-group table behavior described in the issue, including a single editable row with components and rows without an edit container. Identify the frontend entry point responsible for table headers and edit-container styling. Done means headers remain visible when components need them and unintended empty styled rows no longer appear.

Written by the indexing model from the issue text.