LU-10551 lod: obd_fid_alloc() could start a nested trans

LU-10551 lod: obd_fid_alloc() could start a nested trans

* obd_fid_alloc() could possibly start a nested transaction, which
  would reset the OI cache. So we add a
  osd_thread_info::oti_ins_cache_depth to prevent clearing OI cache
  in the nested trnasaction.

* Add more debug mesages in osd_idc_find_or_init()/
  osd_idc_find_and_init()

Test-Parameters: alwaysuploadlogs envdefinitions=PTLDEBUG=-1 testlist=sanity-pfl ostfilesystemtype=zfs mdtfilesystemtype=zfs mdscount=2 mdtcount=4
Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Change-Id: Id75fd1787ffc0f47bbf110d460f23db6c34670da
Reviewed-on: https://review.whamcloud.com/31268
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>