Update Outdated Text Resource IDs in /altinn-studio/reference/ux/texts/#endre-standardtekster-og-feilmeldinger-i-en-applikasjon

### Description

The documentation at `https://docs.altinn.studio/nb/altinn-studio/reference/ux/texts/#endre-standardtekster-og-feilmeldinger-i-en-applikasjon` uses old text resource IDs that are no longer valid in images and examples. Users have provided feedback indicating that the examples provided in the documentation do not work as expected, leading to confusion.

The example uses the IDs `form_filler.file_uploader_validation_error_file_number_1` and `form_filler.file_uploader_validation_error_file_number_2` which have been replaced by `file_uploader_validation_error_file_number.` This issue was raised in an external [Slack thread](https://altinn.slack.com/archives/C02EJ9HKQA3/p1744199947642659).

The examples and images in the documentation should be updated to use valid text resource IDs to ensure they work correctly and avoid user confusion.

### Additional Information

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### Tasks

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### Acceptance Criterias

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Open the documentation section at /altinn-studio/reference/ux/texts/#endre-standardtekster-og-feilmeldinger-i-en-applikasjon and search for the two outdated resource IDs. Update the examples and images to use file_uploader_validation_error_file_number., then verify that the documented examples no longer contain the replaced IDs.

Written by the indexing model from the issue text.