libtracker-miner: Don't delete nie:contentCreated when updating files
libtracker-miner: Don't delete nie:contentCreated when updating files

Fixes NB#232574, nie::ContentCreated is updated when the mtime of a file changes

outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker