[Security Solution] Improve versioning of EBT events - fix schema (#238383)

**Partially addresses: #140369**

## Summary

This PR fixes the schema that I forgot to update in #238278.

Co-authored-by: Georgii Gorbachev <georgii.gorbachev@elastic.co>
(cherry picked from commit 82b2d2d)

Author: jkelas

x-pack/solutions/security/plugins/security_solution/public/common/lib/telemetry/events/rule_upgrade/index.ts

@@ -25,6 +25,13 @@ export const ruleUpgradeFlyoutButtonClickEvent: RuleUpgradeTelemetryEvent = {
         optional: false,
       },
     },
+    eventVersion: {
+      type: 'integer',
+      _meta: {
+        description: 'Indicates the version of the event',
+        optional: false,
+      },
+    },
   },
 };
 
@@ -51,6 +58,13 @@ export const ruleUpgradeOpenFlyoutEvent: RuleUpgradeTelemetryEvent = {
         optional: false,
       },
     },
+    eventVersion: {
+      type: 'integer',
+      _meta: {
+        description: 'Indicates the version of the event',
+        optional: false,
+      },
+    },
   },
 };