LU-12236 tests: add tests for LNET network namespace

LU-12236 tests: add tests for LNET network namespace

This patch adds tests for LNET for this feature.

Test-Parameters: trivial testlist=sanity-lnet
Signed-off-by: Aurelien Degremont <degremoa@amazon.com>
Change-Id: I2320e5da1beef30be5dcca9529fa838fc9304876
Reviewed-on: https://review.whamcloud.com/35666
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <hornc@cray.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>