tests: log error which happens during connect and wait longer for stats socket

tests: log error which happens during connect and wait longer for stats socket

Intermittently, a test would start VPP, but no testcases would execute.
This would be more probable apparent during the high load or if there
is another testcase dumping the core at that moment.
Adding the logging to the connection revealed it was the stats socket
connection erroring with error -2. Increasing the deadline
from 3 seconds to 5 minutes has eliminated this error.

Change-Id: I40bd7e642abb9e2aef0238c612e4c34781de5db2
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
Type: test