This includes

• sage_docbuild: fails when cache cannot be saved #33064: do not fail when docbuild cache cannot be saved
• remove dochtml label from some tests that don't need docs installed
• add dochtml label to some tests that need docs installed
• use dochtml as default option only when html docs are installed

Depends on #33064

CC: @jhpalmieri

Component: doctest framework

Author: Gonzalo Tornaría

Branch/Commit: 88dd9f3

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/33085