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 ce9f204ac493f000cd3020e195fd5038d0cec1e2)
1 file changed