Removes duplicate sources from SystemUIRobo-stub

The duplicate sources seem to be the reason for the Dumpable dependency
issue in the attached bug.

Fix: 358864027
Test: m SystemUIRobo-stub
Test: atest SystemUiRoboTests
Flag: NONE build change only
Change-Id: Iba441488783feb891c84aba11841884b9eb51d37