build-docs: Add option to disable doxygen/sphinx docs (#66928)

Doxygen documentation takes very long to build, when making releases we
want to get the normal documentation up earlier so that we don't have to
wait for doxygen documentation.

This PR just adds the flag to disable doxygen builds, I will then later
make a PR that changes the actions to first build the normal docs and
another job to build the doxygen docs.