* E2E: fix scaling test assertion for extra Windows host
The scaling test assumes that all nodes will receive the system job. But the job
can only run on Linux hosts, so the count will be wrong if we're running a
Windows host as part of the cluster. Filter the expected count by the OS.
While we're touching this test, let's also migrate it off the legacy framework.
* address comments from code review
* func: remove validation scaling for system jobs and dont canonicalize to 1
* test: update test to validate for 0 and improve error message
* func: remove the canonicalization to 1 from system jobs
* docs: add changelog
* func: add test for scaling system jobs
* temp: add logging to debug test
* fix: clean up after test is done
* fix: scaled down jobs will still have the stop allocation, update test to account for it
* Update the e2e test to accomodate for system jobs to have an alloc per node
* fix: filter to only count ready nodes on the node count
* fix: remove the datacenter constrain from the system job definition
* fix: compare alloc IDs to avoid flaky tests when verifying no alloc was stoped
* fix: remove duplicated code
