Clarify Zuul Ram and HDD usage graphs
Clarify Zuul Ram and HDD usage graphs

Make it clear that these values are percentages. We update labels to
convey that and scale the values so that we get 71% instead of 7.145.

Change-Id: I64bb9cfa536c2ba395be0264839a7a50929d7477

openstack-infra/project-config,openstack-infra/project-config