Fully migrate CI from Jenkins to Azure Pipelines

[nbolton]

Problem

Azure is used for the day to day CI because we can easily build on more Linux distros for free and it's on-demand (whereas for Jenkins, there's more manual process and it's not free). We initially planned to use Azure for day to day CI and keep Jenkins for the release build, but Jenkins has a very high maintenance time-cost.

Solution

Fully migrate CI from Jenkins to Azure Pipelines (for both day-to-day CI and release builds).