`nbev_docs` Should give an option to disable the process of "updating tlmgr" and "updating existing packages"

Provide a minimally reproducible example

Run nbdev_docs on a Server in some place where network environment is somewhat different,
and the project contains a notebook with quarto raw block requireing pdf format:

format: 
  html:
    code-fold: true
  pdf:
      toc: true

Due to the network issues,
the command would stuck at

running xelatex - 1
  This is XeTeX, Version 3.141592653-2.6-0.999996 (TeX Live 2024) (preloaded format=xelatex)
   restricted \write18 enabled.
  entering extended mode
  
updating tlmgr

updating existing packages

and it never succeeds, as many related issues reported.

Some background on minimal reproducible examples

Related issues include:
https://github.com/quarto-dev/quarto-cli/issues/1312
https://github.com/quarto-dev/quarto-cli/discussions/7380

Where to host your mimimal reproducible example

TODO

Comienza reproduciendo el problema con nbdev_docs en un notebook que contenga el bloque raw de Quarto mostrado, y sigue el punto de entrada donde se emiten “updating tlmgr” y “updating existing packages”. La tarea debería incluir una opción que deshabilite ambos pasos de actualización y evite que el comando se quede bloqueado en un entorno de red restringida.