Fixed cassini vims sun_position (#594)

* Fixed cassini vims sun_position

* Fixed changed env var

tests/pytests/data/isds/cassinivims_isd.json

@@ -1759,24 +1759,35 @@
     "reference_frame": 1
   },
   "sun_position": {
-    "spk_table_start_time": 188863621.78065246,
-    "spk_table_end_time": 188863621.78065246,
-    "spk_table_original_size": 1,
+    "spk_table_start_time": 188863301.78065246,
+    "spk_table_end_time": 188863941.78065246,
+    "spk_table_original_size": 2,
     "ephemeris_times": [
-      188863621.78065246
+      188863301.78065246,
+      188863941.78065246
     ],
     "positions": [
       [
-        813057365.4425942,
-        -998564700.0216758,
-        -447361435.3093895
+        813054383.7710307,
+        -998568164.2868103,
+        -447361909.40395075
+      ],
+      [
+        813060344.7276177,
+        -998561235.247165,
+        -447360961.0451849
       ]
     ],
     "velocities": [
       [
-        9.313995036182925,
-        10.826626183056739,
-        1.481810430272366
+        9.321451864222995,
+        10.8250291660917,
+        1.4812807197244837
+      ],
+      [
+        9.306535994441248,
+        10.82821277135238,
+        1.4823409901909763
       ]
     ],
     "reference_frame": 1

tests/pytests/test_util.py

@@ -89,8 +89,8 @@ def pvl_four_group():
     # Mock of the DataDirectory group
     return """
     Group = DataDirectory
-      Base         = $ISIS3DATA/base
-      Messenger    = $ISIS3DATA/messenger
+      Base         = $ISISDATA/base
+      Messenger    = $ISISDATA/messenger
     EndGroup
     """