LU-9120 lnet: add lnet_health_sensitivity

LU-9120 lnet: add lnet_health_sensitivity

Add lnet_health_senstivity value. This value determines the amount
the NI health value is decremented by. The value defaults to 0,
which turns off the health feature by default. The user needs
to explicitly turn on this feature. The assumption is that many sites
will only have one interface in their nodes. In this case the
health feature will not increase the resiliency of their system.

Test-Parameters: forbuildonly
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: I23f70b00f270803e5d296033e36a3a09986fd3cf
Reviewed-on: https://review.whamcloud.com/32762
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Reviewed-by: Sonia Sharma <sharmaso@whamcloud.com>
Tested-by: Jenkins
Reviewed-by: Chris Horn <hornc@cray.com>