LU-16518 osp: remove unused osp_txn_info() and friends

LU-16518 osp: remove unused osp_txn_info() and friends

The 'struct osp_txn_info' is no longer used anywhere. So
we no longer need to store this on OSP threads.

Fixes: 0ba690a526be ("LU-7251 osp: do not assign commit callback to every thandle")
Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I8dd5c20c8a9e667aa1ff98cc53430f44f8376ef9
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58412
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>