[Fleet]: Outdated screenshot for Agents tab action menu on Upgrade Elastic Agent page

**Description**

The screenshot showing the **Agents** tab action menu on the *Upgrade Elastic Agent* documentation page is outdated and no longer matches the current UI in Fleet. This may confuse users who are following the guide and cannot locate the controls shown in the docs.

** Affected Page**

https://www.elastic.co/docs/reference/fleet/upgrade-elastic-agent#upgrade-an-agent

**Current Screenshot (in docs)**

**Expected Screenshot (current UI)**

**Expected Result**
- Screenshot in the documentation should be updated to reflect the current Fleet UI for the **Agents** tab action menu, so users see an accurate representation of the controls and steps.

**Build Details**

```
VERSION: 9.4.0
Build: 101544
Commit: b2e39752e03b56f48f51943214475ddba1f8e974
```