Replace duration names with duration format
What does this MR do and why?
This replaces the subjective duration names we intended to label endpoints with to a duration format.
This means that we will now need to specify a string for the duration
target, because symbols with a .
in them don't work.
This is coming from the conversation in gitlab-com/gl-infra/scalability#1315 (comment 692020658)
Edited by Bob Van Landuyt