[AA4AM] Remove multiple agents for build/deploy

[mikefactorial]

Is your feature request related to a problem? Please describe.
A side effect of supporting the build completion triggers was the need to have multiple pipeline runners and as a result needed to load required packages multiple times.

Describe the solution you'd like
Remove the old build completion pipelines and update the latest pipelines to use a single agent.

[devkeydet]

Let's make the work to do the remove the old build completion pipelines to another issue and just focus this on the optimization of the pipeline.