Revert "Don't fail the build if UploadPrebuilts fails.  Show warning instead."
Revert "Don't fail the build if UploadPrebuilts fails.  Show warning instead."

We want to revert this because prebuilts can become invalidated if the PFQ uprevs with no prebuilts.

This reverts commit ebd61e09f807418d3550d92639c22a70407deee1

Change-Id: Ia1cebdc84b81f7fcac5c88bdfe1569e6e050c08f
Reviewed-on: http://gerrit.chromium.org/gerrit/6671
Reviewed-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>
Tested-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>

bpsinc-native/src_third_party_chromite,zhang0137/chromite,coreos/chromite,bpsinc-native/src_third_party_chromite,coreos/chromite,bpsinc-native/src_third_party_chromite,coreos/chromite,chadversary/chromiumos.chromite,chadversary/chromiumos.chromite,zhang0137/chromite,zhang0137/chromite