fix: stop pre-filtering potential known CPE URLs

Previously when building the known CPE index, there was logic to
de-duplicate processing based on the normalized CPE name; however, this
means a significant number of known CPE's don't get indexed because the
first instance of that name didn't have a supported collection url but a
later one did.  This isn't code that executes at runtime in syft so
de-duplicating the processing for performance isn't really necessary
here and it doesn't add much to the total runtime anyways

Signed-off-by: Weston Steimel <commits@weston.slmail.me>