[ApplicationInsights] Enable AAD Auth

[RohitRanjanMS]

Enabling AAD Authentication in the ApplicationInsights worker package is achieved by configuring the APPLICATIONINSIGHTS_AUTHENTICATION_STRING. This configuration ensures a smooth Azure Active Directory Authentication experience across all ApplicationInsights pipelines.

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I will update the doc after the release.

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• I have added all required tests (Unit tests, E2E tests)

[jviau]

Given that TelemetryConfiguration is already used in the IOptions pattern, we can directly configure the credential on it. No need to go through FunctionsApplicationInsightsOptions.

Comment addressed.