Fix various trivial problems (#36953)

1. remove `TEST_CONFLICTING_PATCHES_WITH_GIT_APPLY`
* it defaults to false and is unlikely to be useful for most users (see
#22130)
* with new git versions (>= 2.40), "merge-tree" is used,
"checkConflictsByTmpRepo" isn't called, the option does nothing.
2. fix fragile `db.Cell2Int64` (new: `CellToInt`)
3. allow more routes in maintenance mode (e.g.: captcha)
4. fix MockLocale html escaping to make it have the same behavior as
production locale

models/db/convert.go

@@ -5,12 +5,11 @@ package db
 
 import (
 	"fmt"
-	"strconv"
 
-	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 
 	"xorm.io/xorm"
+	"xorm.io/xorm/convert"
 	"xorm.io/xorm/schemas"
 )
 
@@ -74,15 +73,14 @@ WHERE ST.name ='varchar'`)
 	return err
 }
 
-// Cell2Int64 converts a xorm.Cell type to int64,
-// and handles possible irregular cases.
-func Cell2Int64(val xorm.Cell) int64 {
-	switch (*val).(type) {
-	case []uint8:
-		log.Trace("Cell2Int64 ([]uint8): %v", *val)
-
-		v, _ := strconv.ParseInt(string((*val).([]uint8)), 10, 64)
-		return v
+// CellToInt converts a xorm.Cell field value to an int value
+func CellToInt[T ~int | int64](cell xorm.Cell, def T) (ret T, has bool, err error) {
+	if *cell == nil {
+		return def, false, nil
 	}
-	return (*val).(int64)
+	val, err := convert.AsInt64(*cell)
+	if err != nil {
+		return def, false, err
+	}
+	return T(val), true, err
 }