Remove "public" download feature.

It was never a supported API, and has been reported as causing
security issues, so remove it.

Bug: 111084083
Test: builds
Change-Id: I26345b192ffd55216bb8c8fdb82cb5869d68d3db
(cherry picked from commit 35e123117be9ec5d61dbaea60f6eac06c0e80dc4)
1 file changed