LU-16233 build: Add always target for SUSE15 SP3 LTSS

LU-16233 build: Add always target for SUSE15 SP3 LTSS

SUSE 15 SP3 LTSS kernel version 5.3.18-150300.59.93
(and later) breaks lustre build tests which expect
conftest.i to be generated.

HPE-bug-id: LUS-11286
Test-Parameters: trivial
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: If23e9b31b537878a43075ffff62a99906f47fd9a
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/48833
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>