LU-9771 clio: no glimpse for data immutable file

LU-9771 clio: no glimpse for data immutable file

When merging a layout to an existing file as a mirror, client will
report the size and blocks to the MDT, which will be set to the MDT
object. In that case, if the MDT discovers a mirrored file in
READ_ONLY state, it will report the size and blocks. Clients should
take this advantage and skip glimpse.

Test-Parameters: testlist=sanity-flr
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: I60831689116e6c5dd0311dea62b91dd0ae3cfd56
Reviewed-on: https://review.whamcloud.com/29084
Tested-by: Jenkins
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>