Fix Instance Manager for Linux Consumption Running on Legion

[Tonewall]

Issue describing the changes in this PR

Cherry-picked #11072 into release/4.40.

CV1 Migration pods are starting with the incorrect instance manager. Fixing the AddWebJobsScriptHost() to choose the correct instance manager based on the environment

Pull request checklist

IMPORTANT: Currently, changes must be backported to the in-proc branch to be included in Core Tools and non-Flex deployments.

• Backporting to the in-proc branch is not required
  • in-proc already checks for IsLinuxConsumptionOnLegion() for LegionInstanceManager Code
• 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
• My changes do not require diagnostic events changes
  • Otherwise: I have added/updated all related diagnostic events and their documentation (Documentation issue linked to PR)
• I have added all required tests (Unit tests, E2E tests)

Additional information

Additional PR information