Success :-)!
After digging around in the android sqlite db’s, I finally found the source of that entry. It was in
/data/data/com.android.providers.downloads/databases/downloads.db
After removing this file, it gets rebuild and I am able to access the gallery from within Android apps again. Currently, all preview images are broken. New pictures are shown. But finally the functionality is back. Maybe cleaning the gallery cache and rebuilding it, also solves this issue.
So, if someone comes over here with the same problem. Steps:
ssh into your decvice
devel-su su
lxc-attach -n aliendalvik – /system/bin/sh
rm /data/data/com.android.providers.downloads/databases/downloads.db
exit
exit
exit