Chore: Move to centos8-builder

jjb/vnfrqts/vnfrqts-guidelines.yaml
jjb/vnfrqts/vnfrqts-requirements.yaml
jjb/vnfrqts/vnfrqts-testcases.yaml
jjb/vnfrqts/vnfrqts-usecases.yaml
jjb/vnfsdk/vnfsdk-dovetail-integration-python.yaml
jjb/vnfsdk/vnfsdk-functest.yaml
jjb/vnfsdk/vnfsdk-lctest.yaml
jjb/vnfsdk/vnfsdk-model.yaml
jjb/vnfsdk/vnfsdk-pkgtools-python.yaml
jjb/vnfsdk/vnfsdk-refrepo.yaml
jjb/vnfsdk/vnfsdk-validation.yaml
jjb/vvp/vvp-documentation.yaml
jjb/vvp/vvp-em.yaml
jjb/vvp/vvp-oom.yaml
jjb/vvp/vvp-regression.yaml

Issue-ID: CIMAN-33
Signed-off-by: Bengt Thuree <bthuree@linuxfoundation.org>
Change-Id: Ibad75782a1f0842fad2709995627f4441523d215