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/repo/repo_unit.go

@@ -227,7 +227,11 @@ func (cfg *ProjectsConfig) IsProjectsAllowed(m ProjectsMode) bool {
 func (r *RepoUnit) BeforeSet(colName string, val xorm.Cell) {
 	switch colName {
 	case "type":
-		r.Type = unit.Type(db.Cell2Int64(val))
+		var err error
+		r.Type, _, err = db.CellToInt(val, unit.TypeInvalid)
+		if err != nil {
+			setting.PanicInDevOrTesting("Unable to convert repo unit (id=%d) type: %v", r.ID, err)
+		}
 		switch r.Type {
 		case unit.TypeExternalWiki:
 			r.Config = new(ExternalWikiConfig)