Alerting: Refactor integration tests (#99519)

---------

Signed-off-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>
(cherry picked from commit af663dadc7)

pkg/tests/api/alerting/api_backtesting_test.go

@@ -4,8 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"net/http"
-	"os"
-	"path/filepath"
+	"path"
 	"testing"
 
 	"github.com/grafana/grafana-plugin-sdk-go/data"
@@ -23,7 +22,7 @@ import (
 )
 
 func TestBacktesting(t *testing.T) {
-	dir, path := testinfra.CreateGrafDir(t, testinfra.GrafanaOpts{
+	dir, grafanaPath := testinfra.CreateGrafDir(t, testinfra.GrafanaOpts{
 		DisableLegacyAlerting: true,
 		EnableUnifiedAlerting: true,
 		DisableAnonymous:      true,
@@ -34,7 +33,7 @@ func TestBacktesting(t *testing.T) {
 		EnableLog: false,
 	})
 
-	grafanaListedAddr, env := testinfra.StartGrafanaEnv(t, dir, path)
+	grafanaListedAddr, env := testinfra.StartGrafanaEnv(t, dir, grafanaPath)
 
 	userId := createUser(t, env.SQLStore, env.Cfg, user.CreateUserCommand{
 		DefaultOrgRole: string(org.RoleAdmin),
@@ -44,7 +43,7 @@ func TestBacktesting(t *testing.T) {
 
 	apiCli := newAlertingApiClient(grafanaListedAddr, "admin", "admin")
 
-	input, err := os.ReadFile(filepath.Join("api_backtesting_data.json"))
+	input, err := testData.ReadFile(path.Join("test-data", "api_backtesting_data.json"))
 	require.NoError(t, err)
 	var testData map[string]apimodels.BacktestConfig
 	require.NoError(t, json.Unmarshal(input, &testData))