Skip external config validation if RuntimeDrivenScaling is enabled in Elastic Premium

[soninaren]

Issue describing the changes in this PR

Function host was throwing a host initialization exception when an configuration from external source was used in a trigger binding. The validation / exception was invalid when Runtime driven scaling was enabled for function app was hosted on elastic premium hosting plan. The change here is skips the validation for this specific case.

resolves #6542

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)

Additional information

Additional PR information

[brettsam]

Were you able to test this out before/after in a private site extension?

[soninaren]

Were you able to test this out before/after in a private site extension?

Yes, i tested with private site extension.