ci: Use HTML report instead of PDF

ci: Use HTML report instead of PDF

After the switch to opnfvdocs script for documentation
build, the pdf version of documentation is not generated.
HTML report should be stored inside artifactory instead.

JIRA: VSPERF-324

Change-Id: I42f918721264959ba7c94223204d83ce1fe8ad60
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Christian Trautman <ctrautma@redhat.com>
Reviewed-by: Bill Michalowski <bmichalo@redhat.com>
Reviewed-by: Antonio Fischetti <antonio.fischetti@intel.com>
Reviewed-by: Otto Sabart <osabart@redhat.com>