Add integration test for EZP-21057

"contentService: Unable to delete a content with an empty file attribute"
Fixed EZP-21057: Unable to delete a content with an empty file attribute
(cherry picked from commit dafe993265680b840042fd75df9c045466bde17e)
Merge pull request #417 from ezsystems/EZP-21057

Fix EZP-21057: [contentService] Unable to delete a content with an empty file attribute