Fix image cache periodic task concurrent access bug

This fix catch the exception and ignore a disk file absent
exception. It will defer the image cache clean to next round
image cache periodic task because it's not harmful.
Refer to detailed info, log analysis and root cause in defect.

Change-Id: I3a431bf389658f976edf5c847c04b7e0aac496fd
Closes-Bug: #1261442
Merge "Fix image cache periodic task concurrent access bug"