Enable more revive linter rules (#30608)

Noteable additions:

- `redefines-builtin-id` forbid variable names that shadow go builtins
- `empty-lines` remove unnecessary empty lines that `gofumpt` does not
remove for some reason
- `superfluous-else` eliminate more superfluous `else` branches

Rules are also sorted alphabetically and I cleaned up various parts of
`.golangci.yml`.

modules/templates/htmlrenderer.go

@@ -138,10 +138,9 @@ func wrapTmplErrMsg(msg string) {
 	if setting.IsProd {
 		// in prod mode, Gitea must have correct templates to run
 		log.Fatal("Gitea can't run with template errors: %s", msg)
-	} else {
-		// in dev mode, do not need to really exit, because the template errors could be fixed by developer soon and the templates get reloaded
-		log.Error("There are template errors but Gitea continues to run in dev mode: %s", msg)
 	}
+	// in dev mode, do not need to really exit, because the template errors could be fixed by developer soon and the templates get reloaded
+	log.Error("There are template errors but Gitea continues to run in dev mode: %s", msg)
 }
 
 type templateErrorPrettier struct {