CI: Add new scaleset pools with auto-teardown enabled

[letmaik]

In https://github.com/lsds/sgx-lkl/pull/404 we had to switch from hosted agents back to the current scaleset pools (with VMs reused across builds) for the main branch and release pipeline. This is not ideal since PRs can influence the VM state negatively and any artifact that's published to some public package feed should be built in a fresh environment. Scaleset pools have an auto-teardown option which we don't use because it adds considerable recycling latency (~15min to reset a VM), however we could create separate scaleset pools with zero standby VMs which do have that option enabled, and use those for the release pipeline and main branch builds.