Use the systemd services instead of miq_workers table

For the purposes of starting and stopping workers only looking at the
miq_workers table for the "current" list ignores the fact that there
might be existing services out there already created that are starting,
stopping, or failed and don't have a record tracking them in the
miq_workers table.

app/models/miq_server/worker_management/monitor/quiesce.rb

@@ -36,8 +36,6 @@ def quiesce_workers_loop
     miq_workers.each do |w|
       if w.containerized_worker?
         w.delete_container_objects
-      elsif w.systemd_worker?
-        w.stop_systemd_worker
       else
         stop_worker(w)
       end

app/models/miq_worker.rb

@@ -128,9 +128,20 @@ def self.enough_resource_to_start_worker?
     MiqServer.my_server.enough_resource_to_start_worker?(self)
   end
 
+  def self.cleanup_failed_workers
+    if containerized_worker?
+    elsif systemd_worker?
+      failed_services.each do |service|
+        cleanup_systemd_worker(service)
+      end
+    end
+  end
+
   def self.sync_workers
+    cleanup_failed_workers
+
     w       = include_stopping_workers_on_synchronize ? find_alive : find_current_or_starting
-    current = w.length
+    current = systemd_worker? ? active_services : w.length
     desired = workers
     result  = {:adds => [], :deletes => []}
 
@@ -143,6 +154,8 @@ def self.sync_workers
         w = w.to_a
         (current - desired).times do
           ww = w.pop
+          # TODO add interface to get worker instance by service name
+          ww = find_by(:guid => ww.split("@"))
           result[:deletes] << ww.pid
           ww.stop
         end

app/models/miq_worker/systemd_common.rb

@@ -11,6 +11,30 @@ def supports_systemd?
         false
       end
 
+      def systemd_manager
+        @systemd_manager ||= begin
+          require "dbus/systemd"
+          DBus::Systemd::Manager.new
+        end
+      end
+
+      def services
+        systemd_manager.units.select { |unit| unit[:name].start_with?(service_name) }
+      end
+
+      def active_services
+        services.select { |service| service[:active_state] == "active" }.map { |service| service[:name] }
+      end
+
+      def failed_services
+        services.select { |service| service[:active_state] == "failed" }.map { |service| service[:name] }
+      end
+
+      def cleanup_systemd_worker(unit_name, runtime: false)
+        # TODO cleanup unit settings
+        systemd_manager.DisableUnitFiles([unit_name], runtime)
+      end
+
       def ensure_systemd_files
         target_file_path.write(target_file) unless target_file_path.exist?
         service_file_path.write(unit_file) unless service_file_path.exist?
@@ -118,10 +142,7 @@ def stop_systemd_unit(mode: "replace")
     private
 
     def systemd
-      @systemd ||= begin
-        require "dbus/systemd"
-        DBus::Systemd::Manager.new
-      end
+      self.class.systemd_manager
     end
 
     def service_base_name