LU-9780 tests: Testing Round-Robin allocation

LU-9780 tests: Testing Round-Robin allocation

Adding a test for fix in LU-977 which shows that
in absence of protection to lqr_start_idx there is
possibility of imblance in allocating objects on OSTs
with round-robin algorithm.

This test checks the protection of lqr_start_idx by using
a new reproducer, rr_alloc which uses MPI to create files in
parallel, and checking the even file distribution over OSTs.

Distribution check formula is adjusted as per implementation,i.e
some factors like - exhaustion of pre-created objects and counter
‘lrq_start_count’(lod_qos.c) reseed are also taken care so that
object allocation is not affected by these factors.

Test-Parameters: trivial osscount=3 clientcount=6                  envdefinitions=ONLY=rr_alloc testlist=parallel-scale
Signed-off-by: Ashish Maurya <ashish.maurya@seagate.com>
Signed-off-by: Rahul Deshmukh <rahul.deshmukh@seagate.com>
Signed-off-by: Elena Gryaznova <c17455@cray.com>
Cray-bug-id: MRP-2723
Reviewed-by: Reviewed-by: Vladimir Saveliev <c17830@cray.com>
Reviewed-by: Vikram Jadhav <jadhav.vikram@seagate.com>
Change-Id: I55f798c6dc8e607f002365f4a22ccf59a454fe1d
Reviewed-on: https://review.whamcloud.com/28075
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Alexey Lyashkov <c17817@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>