[8.6] [Fleet] fix for rolling upgrade for <=2h (#148502)

## Summary

Fix for rolling upgrade in 8.6 branch. 
Related:
https://github.com/elastic/ingest-dev/issues/1278#issuecomment-1372100383
Related:
https://github.com/elastic/kibana/pull/148240#discussion_r1060630064

When Maintenance window was set to 1h or 2h, all agents started to
upgrade immediately.
This is because Fleet Server calculated the rollout period from `start :
expiration - minDur (2h)`.
For 1 and 2h, expiration was set to `start + dur`, so the period was set
to 0. As a fix, added a longer expiration for these cases (`2 * dur`).

Only adding this fix for 8.6, as the feature changes in 8.7.

When choosing 1 or 2h, 1 agent starts to upgrade immediately, and the
rest will be scheduled later.
Aborting works for the remaining agents.

<img width="1041" alt="image"
src="https://user-images.githubusercontent.com/90178898/211026957-4abc6120-defd-4bfd-8b2d-b9ade9cd5b57.png">


### Checklist

- [ ] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/fleet/server/services/agents/upgrade.test.ts

@@ -13,6 +13,7 @@ import { createAppContextStartContractMock } from '../../mocks';
 
 import { sendUpgradeAgentsActions } from './upgrade';
 import { createClientMock } from './action.mock';
+import { getRollingUpgradeOptions } from './upgrade_action_runner';
 
 describe('sendUpgradeAgentsActions (plural)', () => {
   beforeEach(async () => {
@@ -102,3 +103,45 @@ describe('sendUpgradeAgentsActions (plural)', () => {
     }
   });
 });
+
+describe('getRollingUpgradeOptions', () => {
+  it('should set longer expiration for 1h duration', () => {
+    const options = getRollingUpgradeOptions('2023-01-06T00:00:00Z', 3600);
+    expect(options).toEqual({
+      expiration: '2023-01-06T02:00:00.000Z',
+      minimum_execution_duration: 3600,
+      start_time: '2023-01-06T00:00:00Z',
+    });
+  });
+  it('should set longer expiration for 2h duration', () => {
+    const options = getRollingUpgradeOptions('2023-01-06T00:00:00Z', 7200);
+    expect(options).toEqual({
+      expiration: '2023-01-06T04:00:00.000Z',
+      minimum_execution_duration: 7200,
+      start_time: '2023-01-06T00:00:00Z',
+    });
+  });
+
+  it('should set normal expiration for longer duration', () => {
+    const options = getRollingUpgradeOptions('2023-01-06T00:00:00Z', 36000);
+    expect(options).toEqual({
+      expiration: '2023-01-06T10:00:00.000Z',
+      minimum_execution_duration: 7200,
+      start_time: '2023-01-06T00:00:00Z',
+    });
+  });
+
+  it('should set min expiration for no duration', () => {
+    const options = getRollingUpgradeOptions('2023-01-06T00:00:00Z');
+    expect(options).toEqual({
+      expiration: '2023-01-06T02:00:00.000Z',
+      minimum_execution_duration: 7200,
+      start_time: '2023-01-06T00:00:00Z',
+    });
+  });
+
+  it('should return empty options for no start time, no duration', () => {
+    const options = getRollingUpgradeOptions();
+    expect(options).toEqual({});
+  });
+});

x-pack/plugins/fleet/server/services/agents/upgrade_action_runner.ts

@@ -148,18 +148,24 @@ export async function upgradeBatch(
 
 const MINIMUM_EXECUTION_DURATION_SECONDS = 60 * 60 * 2; // 2h
 
-const getRollingUpgradeOptions = (startTime?: string, upgradeDurationSeconds?: number) => {
+export const getRollingUpgradeOptions = (startTime?: string, upgradeDurationSeconds?: number) => {
   const now = new Date().toISOString();
   // Perform a rolling upgrade
   if (upgradeDurationSeconds) {
+    const minExecutionDuration = Math.min(
+      MINIMUM_EXECUTION_DURATION_SECONDS,
+      upgradeDurationSeconds
+    );
     return {
       start_time: startTime ?? now,
-      minimum_execution_duration: Math.min(
-        MINIMUM_EXECUTION_DURATION_SECONDS,
-        upgradeDurationSeconds
-      ),
+      minimum_execution_duration: minExecutionDuration,
       expiration: moment(startTime ?? now)
-        .add(upgradeDurationSeconds, 'seconds')
+        .add(
+          upgradeDurationSeconds <= MINIMUM_EXECUTION_DURATION_SECONDS
+            ? minExecutionDuration * 2
+            : upgradeDurationSeconds,
+          'seconds'
+        )
         .toISOString(),
     };
   }