LU-11490 tests: fix rr_alloc() test to use FSNAME

LU-11490 tests: fix rr_alloc() test to use FSNAME

Patch fixes rr_alloc() test to use FSNAME instead of lustre in
the parameter path.

Test-Parameters: testlist=trivial testlist=parallel-scale envdefinitions=ONLY=rr_alloc
Signed-off-by: Elena Gryaznova <c17455@cray.com>
Cray-bug-id: LUS-5955
Reviewed-by: Vladimir Saveliev <c17830@cray.com>
Reviewed-by: Alexander Boyko <c17825@cray.com>
Change-Id: Iebd147dd9757357bf7c8376e9271cb17f4d076a9
Reviewed-on: https://review.whamcloud.com/33333
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Alexandr Boyko <c17825@cray.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>