[8.16](backport #41469) [azure-eventhub] Update input v1 status on start, failure, and stop

[mergify]

Proposed commit message

Update the Elastic Agent status by calling inputContext.UpdateStatus(status.Failed, err.Error()) during the main input lifecycle phases (set up and run). If any of the setup, startup, and run steps fail, the input reports the fatal issue before shutting down.

Without reporting the fatal error, the input logs the error and stops, but users continue to see it as "healthy" in Fleet, causing confusion and making troubleshooting much harder.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Author's Checklist

• Test with wrong event hub credentials (for example, use a connection string from a different namespace)
• Test with wrong storage account credentials (for example, a key from a different storage account or a random string)

How to test this PR locally

• Build a custom agent
• Install the Azure Logs integration
  • set an invalid connection string to test setup() failures
  • set an invalid storage account key to test run() failures

Related issues

• Closes [azure-eventhub] Agent Reports Healthy Status After Input Error Post-Startup integrations#9659

Screenshots

Fatal error during setup() caused by an invalid event hub connection string:

Fatal error during run() caused by an invalid storage account key:

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This is an automatic backport of pull request #41469 done by [Mergify](https://mergify.com).

[botelastic]

This pull request doesn't have a Team:<team> label.

[zmoog]

/test

[zmoog]

The error on "check-logs" seems unrelated to this change.