LU-16048 build: Update ZFS version to 2.1.5

LU-16048 build: Update ZFS version to 2.1.5

Update ZFS version to 2.1.5. The changes are listed in:
https://github.com/openzfs/zfs/releases/tag/zfs-2.1.5

Change-Id: I9f25aafe889f87fb80677e59dbe4679932d8b920
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/48040
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Nathaniel Clark <nclark@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>