net/rds: Don't sleep inside rds_ib_conn_path_shutdown

net/rds: Don't sleep inside rds_ib_conn_path_shutdown

New rds rdma self tests exposed a hang when tearing down
the ib network configs.  This is caused by the shutdown worker
thread sleeping on the wait_event call, which blocks other work
items in the queue. Fix this by changing wait_event to
wait_event timeout, and looping until the wait check succeeds.

Signed-off-by: Allison Henderson <achender@kernel.org>
Link: https://patch.msgid.link/20260518012443.2629206-2-achender@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>