Hide step arrows from numeric "postnummer" field in the address component

[Febakke]

Describe the bug

When focusing on the "postnummer" field in the address component. Step arrows are visible giving the user the possibility to click to add or subtract one from the number in the field. In this case this is something that dosent make sense. It would take a long time to reach 4640 when using it. It would also be impossible to reach 0660 with this functionality. I think it would be better to hide the arrows.

To Reproduce

Steps to reproduce the behavior:

1. Go to an app with the address component
2. Focus or click the "postnummer" field
3. See step arrows

Expected behavior

This is standard behavior for numeric input fields, so in a sense it is expected. But in this case I think it is unnecessary.

Screenshots

Additional info

Tested on macOS (Chrome 84)

[lvbachmann]

Will be handled when implementing Altinn/app-frontend-react#289.