LU-13281 tests: ha.sh improvements

LU-13281 tests: ha.sh improvements

Path adds the possbility to set the different layouts
for clients directories. This allows to run the clients loads
on the directories with DoM, PFL, SEL, etc. including the simple
layouts set on old clients, which is useful for inter-operation
testing.

Patch adds the possibility to split the full client list to
separate subsets by specifying NCLIENTSSET equal to 1 by
default. For NCLIENTSSET=2 two subsets will be created, each
one are passed to corresponding machinefile. This allow
to split the loads which is also useful for inter-operation:
old clients can operate with directories with old layouts while
the new clients operate with directories with new DoM, PFL, SEL,
etc. layouts.
For NCLIENTSSET=2, ${#ha_clients[@]}=4 and
CLIENTSSTRIPE='"-E $((64*1024)) -L mdt -E EOF" "-c -1 "'
layout "-E $((64*1024)) -L mdt -E EOF" will be applied on
even clients ${ha_clients[0]} and ${ha_clients[2]},
layout "-c -1 " will be applied on odd clients ${ha_clients[1]}
and ${ha_clients[3]}.

Test-Parameters: trivial
Cray-bug-id: LUS-6906
Signed-off-by: Elena Gryaznova <elena.gryaznova@hpe.com>
Reviewed-by: Alexander Boyko <alexander.boyko@hpe.com>
Reviewed-by: Vladimir Saveliev <vladimir.saveliev@hpe.com>
Change-Id: Ia6f8c07e3936ea773706c3e79217672c68d77bd0
Reviewed-on: https://review.whamcloud.com/37666
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexandr Boyko <c17825@cray.com>
Reviewed-by: Vladimir Saveliev <c17830@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>