Azure: Rework how we define what to build in the world build

Azure: Rework how we define what to build in the world build

Instead of defining BUILDMAN to the value we'll build in each part of
the matrix job, define a variable with that name and have it list what
to build. This will allow us to reference these multiple times
consistently later on.

Signed-off-by: Tom Rini <trini@konsulko.com>