refactor(tests): merge detect_suggested_procedure into expected_detection

Two overlapping TestTemplate fields (expected_detection: narrative
guidance from imports/leads; detect_suggested_procedure: concrete
commands from approved suggestions) are now one. Blue-side procedure
suggestions target expected_detection directly, appending onto
whatever is already there rather than overwriting it — same
merge-not-overwrite behavior already used for the red side. Existing
detect_suggested_procedure data is folded into expected_detection
before the column is dropped.

backend/tests/test_procedure_suggestions.py

@@ -45,7 +45,7 @@ def template(api, red_lead_headers, technique):
             "mitre_technique_id": "T1059.200",
             "name": "Suggestion source template",
             "attack_procedure": "Run a discovery command on the target.",
-            "detect_suggested_procedure": "Check process creation logs.",
+            "expected_detection": "Check process creation logs.",
         },
     )
     assert resp.status_code == 201, resp.text