Increase timeout for connection on remote import

The source cluster has to shut down an instance before it can be
exported. Doing so can take a while, but the default connection timeout
is only 60 seconds. Adding the shutdown timeout on the receiving cluster
should help.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>
(cherry picked from commit dae91d02)