Divide GetIssueStats query in smaller chunks (#10176)

* Divide GetIssueStats query in smaller chunks

* Skip chunking if count is low enough

* Fix lint

* Define maxQueryParameters

* Remove absMaxQueryParameters because of lint

* Restart CI

* Restart CI

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>

models/models.go

@@ -48,6 +48,12 @@ type Engine interface {
 	SumInt(bean interface{}, columnName string) (res int64, err error)
 }
 
+const (
+	// When queries are broken down in parts because of the number
+	// of parameters, attempt to break by this amount
+	maxQueryParameters = 300
+)
+
 var (
 	x      *xorm.Engine
 	tables []interface{}