docs: Build failure when setting the user in docker run

[Giftzwerg02]

The docs/doxygen-openvadl runs docker using the following command:

docker run --rm \
  -u $(id -u):$(id -g) \
  --group-add $(id -g) \
  -v "$PROJECT_ROOT":/work \
  -w "/work/$RELATIVE_PATH" \
  -e LATEST_VERSION \
  -e PROJECT_NAME \
  -e PROJECT_NUMBER \
  -e PROJECT_BRIEF \
  -e PROJECT_LOGO \
  -e OUTPUT_DIRECTORY \
  -e INPUT \
  "$IMAGE" "$@"

This fails on my machine (Linux, NixOS -> not FHS compliant):

error: Could not open file /work/docs/./obj/doc/open-vadl-docs/html/doxygen_crawl.html for writing

It seems that no files nor directories can be created inside the obj/docs directory. However, deleting

-u $(id -u):$(id -g)

fixes the issue.