Noscript fallback should not be added to the document head

[PRGfx]

The current content of the noscript fallback is not valid for noscript blocks in the head, leading to an HTML validation error.
See matomo-org/matomo#9776

The part of the template should be split into a separate prototype and be added in the body.
That change might however be breaking, as users might have overwritten the prototype and/or the template e.g. to add custom tracking options.