LU-11497 tests: improve ha.sh to set striped dirs

For DNE II testing we need the possibility to create
the striped directories, like it is done in t-f:test_mkdir().
This patch covers the following settings:
-c stripe_count -i mdt_index
-c stripe_count -i <random mdt_index>,
which allows to have the clients work directories with
the same stripe_count but different mdt indexes.

Test-Parameters:trivial
Signed-off-by: Elena Gryaznova <c17455@cray.com>
Cray-bug-id: LUS-5974
Reviewed-by: Vladimir Saveliev <c17830@cray.com>
Reviewed-by: Alexander Boyko <c17825@cray.com>
Change-Id: I6117601e741a95059750149d1c38b402fccb29b7
Reviewed-on: https://review.whamcloud.com/33340
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexandr Boyko <c17825@cray.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>