Fix delete user missed some comments (#21067)
Fix delete user missed some comments (#21067)

There is a mistake in the batched delete comments part of DeleteUser which causes some comments to not be deleted

The code incorrectly updates the `start` of the limit clause resulting in most comments not being deleted.

```go
			if err = e.Where("type=? AND poster_id=?", issues_model.CommentTypeComment, u.ID).Limit(batchSize, start).Find(&comments); err != nil {
```

should be:

```go
			if err = e.Where("type=? AND poster_id=?", issues_model.CommentTypeComment, u.ID).Limit(batchSize, 0).Find(&comments); err != nil {
```

Co-authored-by: zeripath <6a547fdd28db89120bdd70d4af1f9ba672ccd43a@cantab.net>
go-gitea/gitea,go-gitea/gitea,go-gitea/gitea