TMSS-849: added defaults

SAS/TMSS/backend/src/tmss/tmssapp/schemas/subtask_template-observation-1.json

@@ -144,6 +144,7 @@
                 "headerTemplate": "Pipeline {{ self.index }}",
                 "title": "Pipeline",
                 "additionalProperties": false,
+                "default": {},
                 "properties": {
                   "coherent": {
                     "title": "Coherent Stokes Settings",