exceptions: move defrag stats to common counter

Part of making the exception policy stats counters more search
friendly.

Task #7185

etc/schema.json

@@ -6021,11 +6021,6 @@
                             "type": "integer",
                             "description": "Current memory use."
                         },
-                        "memcap_exception_policy": {
-                            "description":
-                                    "How many times defrag memcap exception policy was applied, and which one",
-                            "$ref": "#/$defs/exceptionPolicy"
-                        },
                         "ipv4": {
                             "type": "object",
                             "properties": {
@@ -6163,6 +6158,14 @@
                                     "Consolidated stats on how many times app-layer error exception policy was applied, and which one",
                                 "$ref": "#/$defs/exceptionPolicy"
                             }
+                        },
+                        "defrag": {
+                            "type": "object",
+                            "memcap": {
+                                "description":
+                                        "How many times defrag memcap exception policy was applied, and which one",
+                                "$ref": "#/$defs/exceptionPolicy"
+                            }
                         }
                     }
                 },

src/decode.c

@@ -683,7 +683,7 @@ void DecodeRegisterPerfCounters(DecodeThreadVars *dtv, ThreadVars *tv)
     dtv->counter_defrag_tracker_timeout = StatsRegisterCounter("defrag.wrk.tracker_timeout", tv);
 
     ExceptionPolicySetStatsCounters(tv, &dtv->counter_defrag_memcap_eps, &defrag_memcap_eps_stats,
-            DefragGetMemcapExceptionPolicy(), "defrag.memcap_exception_policy.",
+            DefragGetMemcapExceptionPolicy(), "exception_policy.defrag.memcap.",
             IsDefragMemcapExceptionPolicyStatsValid);
 
     for (int i = 0; i < DECODE_EVENT_MAX; i++) {