log pdu_failures from incoming transactions
log pdu_failures from incoming transactions

... even if we have no EDUs.

This appears to have been introduced in
476899295f5fd6cff64799bcbc84cd4bf9005e33.

matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse