The function does not do any dconf database filtering

* Remove the "Filtering" part from the name because the function
  doesn't do any filtering
* Mention that it can also update the golden files

We don't need to pass it, the function can access the package variable
instead.

Move function calls out of require.NoError for improved readability.

Print the content in multiple lines instead of a single line.

Use delta to colorize the diff of mismatching golden files if delta is
found in the PATH.