Fix flaky connector adapters test (elastic#198396)

Resolves elastic#198388

In this PR, I'm increasing the rule frequency to avoid rule actions
running multiple times when asserting for the action to only have ran
once.

Flaky test runner:
-
https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/7307

(cherry picked from commit 14fa363)

x-pack/test/alerting_api_integration/security_and_spaces/group4/tests/alerting/alerts.ts

@@ -1901,7 +1901,7 @@ instanceStateValue: true
          */
         const response = await alertUtils.createAlwaysFiringSystemAction({
           reference,
-          overwrites: { schedule: { interval: '1s' } },
+          overwrites: { schedule: { interval: '1m' } },
         });
 
         expect(response.status).to.eql(200);