feat(crons): Add "volume_detection" result to clock-tick

This will be used to inform the clock tick tasks that the tick detected
an abnormal amount of check-in volume for the previous minute.

Part of getsentry/sentry#79328

Author: evanpurkhiser

examples/monitors-clock-tick/1/example-volume-abnormal.json

@@ -0,0 +1,4 @@
+{
+  "ts": 1714072962,
+  "volume_detection": "abnormal"
+}

examples/monitors-clock-tick/1/example-volume-normal.json

@@ -0,0 +1,4 @@
+{
+  "ts": 1714072962,
+  "volume_detection": "normal"
+}

schemas/monitors-clock-tick.v1.schema.json

@@ -12,6 +12,11 @@
         "ts": {
           "description": "The timestamp the clock ticked at.",
           "type": "number"
+        },
+        "volume_detection": {
+          "description": "The result of the volume anomaly detection for the minute that has been ticked past.",
+          "type": "string",
+          "enum": ["normal", "abnormal"]
         }
       },
       "required": ["ts"]