Update dirac test reference for atlas-orca version

Author: twsearle

src/tests/testoutput/test_dirac.ref

@@ -1,10 +1,10 @@
 Input Dirac increment:Increment valid at time: 2021-06-30T12:00:00Z
     1 variables: ice_area_fraction
     atlas field:
-        ice_area_fraction num: 26553 mean: 3.76605e-05 rms: 6.13682e-03 min: 0.00000e+00 max: 1.00000e+00
+        ice_area_fraction num: 26551 mean: 3.76634e-05 rms: 6.13705e-03 min: 0.00000e+00 max: 1.00000e+00
 
 Covariance(SABER) * Increment:Increment valid at time: 2021-06-30T12:00:00Z
     1 variables: ice_area_fraction
     atlas field:
-        ice_area_fraction num: 26553 mean: 3.76605e-05 rms: 6.13682e-03 min: 0.00000e+00 max: 1.00000e+00
+        ice_area_fraction num: 26551 mean: 3.76634e-05 rms: 6.13705e-03 min: 0.00000e+00 max: 1.00000e+00