LU-11052 obd: remove OBD ops based stats

LU-11052 obd: remove OBD ops based stats

Stats maintained via the OBD operations wrappers (obd_setup(),
obd_cleanup(), ...) are less and less interesting to the point that we
should remove them. The only stats files affected by this are
obdfilter.*.stats, obdfilter.*.exports.*.stats and
obdecho.*.stats. For obdfilter here is a comparison for two racer
runs. With the current OBD ops based stats:

obdfilter.lustre-OST0000.stats=
snapshot_time             1527267354.328068245 secs.nsecs
read_bytes                610 samples [bytes] 4096 4194304 800043008
write_bytes               2196 samples [bytes] 5 4194304 3410224606
setattr                   13545 samples [reqs]
punch                     7682 samples [reqs]
destroy                   2281 samples [reqs]
create                    74 samples [reqs]
statfs                    234 samples [reqs]
get_info                  1 samples [reqs]
connect                   3 samples [reqs]
disconnect                1 samples [reqs]
preprw                    2806 samples [reqs]
commitrw                  2806 samples [reqs]
ping                      422 samples [reqs]

And after the OBD ops bases stats have been removed:

obdfilter.lustre-OST0000.stats=
snapshot_time             1527168813.867472974 secs.nsecs
read_bytes                200 samples [bytes] 4096 4194304 231366656
write_bytes               1703 samples [bytes] 5 4194304 1220864892
getattr                   337 samples [reqs]
setattr                   6358 samples [reqs]
punch                     2880 samples [reqs]
destroy                   2000 samples [reqs]
create                    71 samples [reqs]
statfs                    2148 samples [reqs]
get_info                  4 samples [reqs]

Changes to obdfilter.lustre-OST0000.exports.*.stats are similar.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: If4fb7022a3de0aa61905212eaab07b94c1687c68
Reviewed-on: https://review.whamcloud.com/32602
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Jesse Hanley <hanleyja@ornl.gov>
Reviewed-by: Oleg Drokin <green@whamcloud.com>