Currently, stack_install_service will accept any service name. This is
problematic because a project plugin can pass an invalid name without
noticing. This has been the case in ironic-inspector[0].
This commit ensures that stack_install_service will not silently fail
when passing an invalid service name.
[0] https://review.openstack.org/#/c/424680/
Change-Id: I1a8105bdbaf4aecb630df08da416808bf7180824
Closes-Bug: #1659042