LPS-50330 Use JDBC to retrieve original image content from DB with the legacy logic

Hi @sergiogonzalez,

There were two issues, what are fixed by this commit:

1) As in 6.2 the DLFileEntry have additional fields, like ManualCheckInRequired, and for the upgrade we used our API to get the corresponding DLFileEntry, what leads to SQL related execptions as the Entity and the mapping is not in sync with the DB.

2) The other problem is that the original ImageImpl used the Image table's text_ filed where we stored it in Base64 format, but now we try to load the image through:
```
DLFileEntry dlFileEntry =
				DLFileEntryLocalServiceUtil.fetchFileEntryByAnyImageId(imageId);l
```
But as it will be migrated there, there's no chance that it could exist already there.

So I just created a method to use JDBC to retrieve the Image content form the _text filed as it was working in pre 6.1 versions.

Regards,
Vilmos