[DOCS] Update screenshots of Elastic Defend

[joepeeples]

Description

• Parent docs meta: [DOCS] [META] Rename integration to "Elastic Defend" #2463
• Related dev issue: https://github.com/elastic/security-team/issues/4759

Update all screenshot images that reference the former integration name "Endpoint and Cloud Security" and update with the new name "Elastic Defend."

Topics to update

(May include more, but start here. Also consult the screenshot update PR from the previous renaming in 8.3 for guidance.)

• Install Endpoint Security integration - Consider renaming the files (again) with a different prefix (maybe just defend-*?). We'll update these images when we revise the entire page for the new guided onboarding process (#2457).
  • endpoint-cloud-sec-integrations-page.png
  • endpoint-cloud-security-configuration.png
  • endpoint-cloud-sec-add-agent.png
  • endpoint-cloud-sec-add-agent-detail.png
• Endpoints page - Updated in #2476
  • endpoints-pg.png
  • host-flyout.png
  • integration-pg.png
  • filter-endpoints.png
• Host isolation page - One screenshot to update (#2520):
  • isolated-host.png