fix: use consistent GetUser family functions (#37553) (#37589)

Backport #37553

fixes adding collaborative owners in Actions settings when the user or
organization name contains capital letters.

Fixes #37548

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Nicolas <bircni@icloud.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/common/compare.go

@@ -129,7 +129,7 @@ func GetHeadOwnerAndRepo(ctx context.Context, baseRepo *repo_model.Repository, c
 	if compareReq.HeadOwner == baseRepo.Owner.Name {
 		headOwner = baseRepo.Owner
 	} else {
-		headOwner, err = user_model.GetUserOrOrgByName(ctx, compareReq.HeadOwner)
+		headOwner, err = user_model.GetUserByName(ctx, compareReq.HeadOwner)
 		if err != nil {
 			return nil, nil, err
 		}