LU-9448 lnet: handle empty CPTs

LU-9448 lnet: handle empty CPTs

Make the LND code handle empty CPTs.

If a scheduler is associated with an empty CPT it will have no
threads created. If a NID hashes to that CPT, then pick the
next scheduler which does have at least 1 started thread.
Associate the connection with the CPT of the selected scheduler

Test-Parameters: trivial
Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Change-Id: I8ed83f295fe9852537d4bb063a4d8271c6a45c2c
Reviewed-on: https://review.whamcloud.com/27145
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>