Remove confusing SetEdns0 call (#2718)
Remove confusing SetEdns0 call (#2718)

Remove `SetEdns0` call in `bdns.exchangeOne`. Since we talk over TCP to the production
resolver and we don't do any local validation of DNSSEC records adding the EDNS0 OPT
record is pointless and confusing. Testing against a local `unbound` instance shows you
 don't need to set the DO bit for DNSSEC requests/validation to be done at the resolver
level.
lucasallan/boulder,letsencrypt/boulder,jcjones/boulder,letsencrypt/boulder,jfrazelle/boulder,jcjones/boulder,jfrazelle/boulder,jcjones/boulder,lucasallan/boulder,letsencrypt/boulder,jsha/boulder,ibukanov/boulder,bmw/boulder,bmw/boulder,jsha/boulder,ibukanov/boulder,ibukanov/boulder,jfrazelle/boulder,bmw/boulder,jcjones/boulder,jsha/boulder,lucasallan/boulder,jfrazelle/boulder