LU-11912 tests: fix racing in force_new_seq_all

LU-11912 tests: fix racing in force_new_seq_all

We run force_new_seq in parallel to reduce time spent
on consuming precreated objects.

However this could be racy when multiple MDTs are on
the same MDS, a task could finish for one MDT early
and reset the fail_loc to 0 on MDS while other tasks
are still working on other MDTs.

Replace OBD_FAIL_OSP_FORCE_NEW_SEQ with a new param
prealloc_force_new_seq for osp, so we can control
the seq rollover individually for each osp device.

Change-Id: I52dbd550564ca628a8a85c42951694d58b2b93a9
Fixes: 656fc937cf ("LU-11912 tests: consume precreated objects in parallel")
Signed-off-by: Li Dongyang <dongyangli@ddn.com>