Add performance test with 2 MPI processes

Overlap/Tests/long_tests.json

@@ -21,5 +21,17 @@
             "1",
             "$my_data_dir/Global_1993_2023/SHPC"
 	]
+    },
+    "EGg_1993_2": {
+	"input": "&config_graph_nml max_delta = 4/\n&MAIN_NML I_SLICE=0/\n",
+	"env": {
+            "mpiexec": "$mpiexec"
+	},
+	"description": "Same as EGg_1993_2023, but with 2 MPI processes.",
+	"command": [
+            "$build_dir/Overlap/eddy_graph.sh",
+            "2",
+            "$my_data_dir/Global_1993_2023/SHPC"
+	]
     }
 }