LU-13477 lnet: Force full discovery cycle

LU-13477 lnet: Force full discovery cycle

There are scenarios where there could be a discrepancy between
cached peer information and reality. In these cases what could
end-up happening is incomplete interface information might be
cached because one side determined that the peer didn't require
a PUSH. This will lead to undesired MR behavior, where not all
the interfaces are used for a period of time.

Therefore, it is safer to always force a full discovery cycle:
GET/PUSH to ensure both sides are up-to-date.

In the NMR case, when discovery is turned off, make sure to flag
discovery as complete to avoid stalling the state machine.

Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: Ie49ad11e8ff874206baa268a4ef2d58ebb536ed5
Lustre-change: https://review.whamcloud.com/38322
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/39577
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Cyril Bordage <cbordage@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>