Symlink `config_nml.txt` instead of creating it

`config_nml` should be the same for `test_get_1_outerm` and
`test_set_max_speed`.

Inst_eddies/Tests/short_tests.json

@@ -176,10 +176,7 @@
 	]
     },
     "Set_max_speed": {
-	"create_file": [
-            "config_nml.txt",
-            "&config_nml /\n"
-	],
+	"symlink": ["$PWD/Get_1_outerm/config_nml.txt"],
 	"commands": [
             [
 		"mkdir",
@@ -196,10 +193,7 @@
 	"input": "t\n", "copy": ["$PWD/Get_1_outerm/cont_list.*"]
     },
     "Set_max_speed_noise": {
-	"create_file": [
-            "config_nml.txt",
-            "&config_nml /\n"
-	],
+	"symlink": ["$PWD/Get_1_outerm_noise_2_8/config_nml.txt"],
 	"commands": [
             ["mkdir", "-p", "SHPC/Slice_0/Cyclones"],
             [
@@ -228,10 +222,7 @@
 	"description": "This test is only useful to create input for test Set_max_speed_degenerate. Namelist values were obtained with test_local_extrema."
     },
     "Set_max_speed_degenerate": {
-	"create_file": [
-            "config_nml.txt",
-            "&config_nml /\n"
-	],
+	"symlink": ["$tests_old_dir/SHPC_degenerate/config_nml.txt"],
 	"description": "The SSH value of the extremum is exactly equal to the SSH value of the point next to the extremum, eastward. This points is selected as the point with maximum azimuthal speed. Then good_contour returns a null polyline.",
 	"commands": [
             [