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"

tests/integration/dump_restore_test.go

@@ -20,6 +20,7 @@ import (
 	base "code.gitea.io/gitea/modules/migration"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/test"
 	"code.gitea.io/gitea/services/migrations"
 
 	"github.com/stretchr/testify/assert"
@@ -28,16 +29,9 @@ import (
 
 func TestDumpRestore(t *testing.T) {
 	onGiteaRun(t, func(t *testing.T, u *url.URL) {
-		AllowLocalNetworks := setting.Migrations.AllowLocalNetworks
-		setting.Migrations.AllowLocalNetworks = true
-		AppVer := setting.AppVer
 		// Gitea SDK (go-sdk) need to parse the AppVer from server response, so we must set it to a valid version string.
-		setting.AppVer = "1.16.0"
-		defer func() {
-			setting.Migrations.AllowLocalNetworks = AllowLocalNetworks
-			setting.AppVer = AppVer
-		}()
-
+		defer test.MockVariableValue(&setting.AppVer, "1.16.0")()
+		defer test.MockVariableValue(&setting.Migrations.AllowLocalNetworks, true)()
 		assert.NoError(t, migrations.Init())
 
 		reponame := "repo1"