chore: clean up tests (#37715)

1. use MockVariableValue as much as possible
2. use wg.Go as much as possible instead of Add/Done
3. simplify global lock's DefaultLocker logic to make it easier to test
4. introduce a general approach for getting external service config in
CI
5. remove unclear & unnecessary "t.Skip"
6. use modern generic syntax for remaining "DecodeJSON" calls
7. clarify test result for "list gitignore templates" and "list
licenses"

modules/storage/minio_test.go

@@ -11,20 +11,18 @@ import (
 	"testing"
 
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
 
 	"github.com/minio/minio-go/v7"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestMinioStorage(t *testing.T) {
-	if os.Getenv("CI") == "" {
-		t.Skip("minioStorage not present outside of CI")
-		return
-	}
+	endpoint := test.ExternalServiceHTTP(t, "TEST_MINIO_ENDPOINT", "minio:9000")
 	storageType := setting.MinioStorageType
 	config := &setting.Storage{
 		MinioConfig: setting.MinioStorageConfig{
-			Endpoint:        "minio:9000",
+			Endpoint:        endpoint,
 			AccessKeyID:     "123456",
 			SecretAccessKey: "12345678",
 			Bucket:          "gitea",