With the new release of Sphinx 3.1.0, building blazar pdf docs started
failing with a "! Dimension too large." error.
TeX memory gets exhausted during the pdf build due to the inclusion of
large sample files. With this fix, sample files are included in html but
not in pdf.
Disable other Zuul jobs since some are failing. They will be enabled
again in https://review.opendev.org/#/c/738071/
Change-Id: I1287ebdeab2be521c2d19177560c8467f2acc182
Closes-Bug: #1885250
fe0fea186a