LU-11141 tests: put sanity-quota 61 on slow list

LU-11141 tests: put sanity-quota 61 on slow list

Since the patch for LU-11141, with commit, 6316b42a73f8,
landed, sanity-quota test 61 takes between 20 and 50
minutes to run. Test 61 needs to be added to the slow
list and, thus, will not be run unless the SLOW
variable is true.

Test-Parameters: trivial testlist=sanity-quota
Test-Parameters: envdefinitions="SLOW=yes" testlist=sanity-quota

Signed-off-by: James Nunez <jnunez@whamcloud.com>
Change-Id: I2b6c21996ef2db9472da8838d3f41fed60ba5102
Reviewed-on: https://review.whamcloud.com/32903
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>