LU-18162 kunit: convert llog unit test to LU device

LU-18162 kunit: convert llog unit test to LU device

Convert OBD test to use LU device init/fini rather
than the legacy OBD API.

Test-Parameters: trivial testlist=sanity env=ONLY=60a,ONLY_REPEAT=25
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: Iab7e3109ac061be826b0d7695fcc69e0dee2346d
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58803
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Lijing Chen <lijinc@amazon.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>