Don't send handle validation pool failures for un-important builders.
Don't send handle validation pool failures for un-important builders.

BUG=chromium-os:31896
TEST=Ran unittests.

Change-Id: I9b35143c125254fe63dc278e049c54a3dde27658
Reviewed-on: https://gerrit.chromium.org/gerrit/25409
Reviewed-by: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>
Tested-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>

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