This implements a two-part deletion process for prober domains that were
not deleted properly by the prober (which is usually caused by a transient
network failure). The first time the mapreduce is run, such domains are
soft-deleted, so that their DNS entries can be removed correctly, and then
they are hard-deleted in the subsequent run.
Currently, all domains are hard-deleted the first time this mapreduce
runs, even if they were never soft-deleted correctly, which means that
their published DNS entries won't be correctly handled.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=165612973