duplicates detection: drop support

with the advance of automatic crash reporting the duplicates detection
isn't really necessary anymore.

it also hasn't been all that great. the UI was terrible, the UX was
terrible, the code was expansive, parsing random comments from bugzilla
had potential of crashing drkonqi ...

BUG: 463223
BUG: 473408
BUG: 466919
BUG: 278636
BUG: 264146