Chore: Refactor backend plugin manager/tsdb query data (#34944) (#35172)

Move QueryData method into backend plugin manager which HandleRequest uses to
query data from plugin SDK supported data sources. This allowed us to remove a lot
of code no longer needed.

Ref #21510

Co-authored-by: Will Browne <wbrowne@users.noreply.github.com>
(cherry picked from commit b3e9087557)

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

pkg/plugins/renderer_plugin.go

@@ -30,9 +30,7 @@ func (r *RendererPlugin) Load(decoder *json.Decoder, base *PluginBase,
 
 	cmd := ComposePluginStartCommand("plugin_start")
 	fullpath := filepath.Join(base.PluginDir, cmd)
-	factory := grpcplugin.NewRendererPlugin(r.Id, fullpath, grpcplugin.PluginStartFuncs{
-		OnStart: r.onPluginStart,
-	})
+	factory := grpcplugin.NewRendererPlugin(r.Id, fullpath, r.onPluginStart)
 	if err := backendPluginManager.Register(r.Id, factory); err != nil {
 		return nil, errutil.Wrapf(err, "failed to register backend plugin")
 	}
@@ -48,7 +46,7 @@ func (r *RendererPlugin) Start(ctx context.Context) error {
 	return nil
 }
 
-func (r *RendererPlugin) onPluginStart(pluginID string, client *grpcplugin.Client, logger log.Logger) error {
-	r.GrpcPluginV2 = client.RendererPlugin
+func (r *RendererPlugin) onPluginStart(pluginID string, renderer pluginextensionv2.RendererPlugin, logger log.Logger) error {
+	r.GrpcPluginV2 = renderer
 	return nil
 }