Some issues that have been fixed would manifest by timeouts on
connect, unexpected memory usage on high publish message rate.
Some details:
- Replies were not always GW routed properly because we were looking
at the wrong connection's rsubs
- GW routed replies would not be found because they were tracked
in the subscription's client object, which may not be the same used
to send the reply
- Increased the mqtt timeout to wait for JS replies since in some
tests it was sometimes taking more than the original 2 seconds
- Incoming gateway messages destined for an MQTT internal subscription
may have been rejected as a no interest if the account had service imports
- Don't use time.After(), instead create explicit timer so it can
be stopped when not timing out.
- Unnecessary copy of a slice since we were converting to a string anyway.
Signed-off-by: Ivan Kozlovic <ivan@synadia.com>