Fixes#35936.
When running `OC\Preview\BackgroundCleanupJob`, the main iteration loop
in `run()` expects a folder, however, `getOldPreviewLocations()`
currently does not filter by mimetype and therefore can yield a
non-folder entry which causes an Exception when constructing the Folder
impl.
Filtering for `httpd/unix-directory`, as `getNewPreviewLocations()`
already does, fixes this issue.
Signed-off-by: Dario Mehlich <d.mehlich@gmail.com>
Else the number of files can grow very large very quickly in the preview
folder. Esp on large systems.
This generates the md5 of the fileid. And then creates folders of the
first 7 charts. In that folder is then a folder with the fileid. And
inside there are the previews.
Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>
