Delay categorized watcher posts until host summary is available

- keep categorized grouped sub-runs in RUNNING state when only the grouped check-xml-files.ts artifact has appeared and the parent log has not yet exposed the real host summary
- prevent blank Mattermost grouped-run posts with empty host tables, zero counts, and zero/invalid timing caused by posting too early
- require the categorized watcher to wait for host-level grouped summary data before treating the grouped run as complete

atvm/watcher-service/atvm_run_watcher.py

@@ -753,6 +753,8 @@ def discover_categorized_subruns(
             state = "RUNNING"
             if cancelled:
                 state = "CANCELLED"
+            elif check_ts and not host_results and parent_active:
+                state = "RUNNING"
             elif check_ts or raw_display_name != current_subrun_build or not parent_active:
                 state = "FAILED" if any(result.failures for result in host_results.values()) else "COMPLETED"
             display_name = corrected_categorized_display_name(raw_display_name, list(host_results))
@@ -761,6 +763,8 @@ def discover_categorized_subruns(
                 notes.append("Final `check-xml-files.ts` validation passed.")
             if summary and host_results:
                 notes.append("Host result details were derived from the parent categorized run log summary.")
+            elif check_ts and not host_results and parent_active:
+                notes.append("Grouped reporter XML arrived before the parent run log exposed the final host summary; waiting to post until host details are available.")
             if display_name != raw_display_name:
                 notes.append(f"Child build id was reported as `{raw_display_name}`, but the actual grouped run was inferred from host execution as `{display_name}`.")
             if cancelled: