More flexible TCP Syslog drain shrinking

Shrinking is now dependent on number of messages in the buffer, presence
of dropped messages, and number of sequential failures instead of time
only.
Add better resizing

Always resize *up* after a connection iff the log buffer is smaller than
the current default value for the buffer.
Add convenience functions to obtain drains by type
Removig (now) useless ugprade code
Upgrade procedure for v69.10->v69.11