Replace custom Go formatter with golangci-lint fmt (#37194)

Use `golangci-lint fmt` to format code, replacing the previous custom
formatter tool. https://github.com/daixiang0/gci is used to order the
imports.

`make fmt` performs ~13% faster while consuming ~57% less cpu while
formatting for me.

`GOFUMPT_PACKAGE` is gone because it's using the builtin package from
golangci-lint.

Co-authored-by: Claude (claude-opus-4-6) <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

models/db/engine.go

@@ -11,11 +11,11 @@ import (
 	"reflect"
 	"strings"
 
-	"xorm.io/xorm"
-
 	_ "github.com/go-sql-driver/mysql"  // Needed for the MySQL driver
 	_ "github.com/lib/pq"               // Needed for the Postgresql driver
 	_ "github.com/microsoft/go-mssqldb" // Needed for the MSSQL driver
+
+	"xorm.io/xorm"
 )
 
 var (