The periodic security download ran blocking HTTP on the reactor thread, so a
dead selfcare server stalled RPTPING handling well past PING_TIME * MAX_MISSED
and every peer was timed out and forced to reconnect. Move the security and
alias downloads to the thread pool, bound the DNS and HTTP timeouts below that
budget, and skip a cycle when the previous one is still in flight.
Also drop the redundant interval guard that silently stretched the real retry
period to a multiple of the loop interval, restore the process-wide socket
timeout after a failed DNS lookup, keep existing files and cached passwords
when a download returns an empty or invalid payload, and remove the inherited
50Mb cap on subscriber_ids that production was already close to tripping.
PASS_SECURITY is no longer written to the log.
Rodrigo Pérez