Add events.clear_scroll endpoint to clear event search scrolls

apiserver/schema/services/events.conf

@@ -1304,3 +1304,24 @@ scalar_metrics_iter_raw {
         }
     }
 }
+clear_scroll {
+    "2.18" {
+        description: "Clear an open Scroll ID"
+        request {
+            type: object
+            required: [
+                scroll_id
+            ]
+            properties {
+                scroll_id {
+                    description: "Scroll ID as returned by previous events service calls"
+                    type: string
+                }
+            }
+        }
+        response {
+            type: object
+            additionalProperties: false
+        }
+    }
+}