[Security Solution][Endpoint] Unskip metadata API ftr test

[ashokaditya]

Summary

Adds an error handler block to help debug test setup errors during fleet agent setup for endpoint API ftr tests. Also adds missing header API version.

fixes /issues/151854

flaky ftr test runners

• https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/3223 x 150 (without header) - (1 fail)
• https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/3224 x 50 (all 50 pass)
• https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/3228 x 100 (2 fails)
• https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/3231 x 100 ( 1 fail)
• https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/3241 x 50 ( 2 fails)

Checklist

• Unit or functional tests were updated or added to match the most common scenarios

[elasticmachine]

Pinging @elastic/security-defend-workflows (Team:Defend Workflows)

[ashokaditya]

@elasticmachine merge upstream

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 91ad04a

Metrics [docs]

✅ unchanged

History

• 💔 Build #163291 failed 8555911
• 💔 Build #163267 failed 1eebaec
• 💔 Build #162990 failed e1dbe7d
• 💔 Build #162969 failed 954aa49
• 💔 Build #162754 failed b2ce0cc
• 💔 Build #162709 failed b543b7a

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @ashokaditya