Remove unnecessary dedup logic

The CreateClasspathElements function makes sure that each standalone
library and bootclasspath_fragment on the platform bootclasspath
appear once and once only and each file extracted is unique to the
module so there is no chance that any duplicate files will be used.

Bug: 194063708
Test: m out/soong/hiddenapi/hiddenapi-flags.csv
      - check that this does not change the contents.
Change-Id: I60c02baa4d179293ee0f305375afaa3a8c98e112