Plugins: Remove old code related to Core plugin installs (#44311)

* remove old code

* remove even more

* skip flaky test

pkg/plugins/backend_utils.go

@@ -2,11 +2,8 @@ package plugins
 
 import (
 	"fmt"
-	"path/filepath"
 	"runtime"
 	"strings"
-
-	"github.com/grafana/grafana/pkg/setting"
 )
 
 func ComposePluginStartCommand(executable string) string {
@@ -32,14 +29,3 @@ func ComposeRendererStartCommand() string {
 
 	return fmt.Sprintf("%s_%s_%s%s", "plugin_start", os, strings.ToLower(arch), extension)
 }
-
-func CoreDataSourcePathResolver(cfg *setting.Cfg, pluginRootDirName string) PluginPathResolver {
-	return func() (string, error) {
-		// override mismatch cloud monitoring plugin
-		if pluginRootDirName == "stackdriver" {
-			pluginRootDirName = "cloud-monitoring"
-		}
-
-		return filepath.Join(cfg.StaticRootPath, "app/plugins/datasource", pluginRootDirName), nil
-	}
-}