This commit provides a path to set register the autoscaling feature flag
in release builds, and therefore enabling autoscaling in release
builds. The primary reason that we add this is so that our release docs
tests can pass. Our release docs tests do not have infrastructure in
place to only register snippets from included portions of the docs, they
instead include all docs snippets. Since autoscaling can not be enabled
in release builds, this meant that the autoscaling snippets would fail
in the release docs tests. To address then, we need the ability to
enable autoscaling in the release docs tests which we can now do with
the system property added here. This system property will be removed
when autoscaling is ready for release.