chore: Fix tests using GetIndependentShardScalingMode (#3799)

Author: lantoli

internal/testutil/acc/independent_shard_scaling.go

@@ -6,7 +6,6 @@ import (
 	"net/http"
 	"os"
 
-	"github.com/mongodb-forks/digest"
 	"github.com/mongodb/terraform-provider-mongodbatlas/internal/config"
 )
 
@@ -16,16 +15,8 @@ func GetIndependentShardScalingMode(ctx context.Context, projectID, clusterName
 	if err != nil {
 		return nil, nil, err
 	}
-
 	req.Header.Add("Accept", "*/*")
-
-	transport := digest.NewTransport(os.Getenv("MONGODB_ATLAS_PUBLIC_KEY"), os.Getenv("MONGODB_ATLAS_PRIVATE_KEY"))
-	httpClient, err := transport.Client()
-	if err != nil {
-		return nil, nil, err
-	}
-
-	resp, err := httpClient.Do(req)
+	resp, err := ConnV2().GetConfig().HTTPClient.Do(req)
 	if err != nil || resp == nil {
 		return nil, resp, err
 	}