Consolidate Azure CLI credential instances in test helper

[damonbarry]

Surgical cherry-pick of 5317cde from the release/1.5 branch. This update optimizes our use of Azure CLI credentials in a helper class so tests don't needlessly invoke az account get-access-token multiple times. This was an important change for end-to-end tests on Debian 11/arm32v7 (1.5 only); the redundant credential commands don't seem to cause failures in 1.6 test runs, but there's no reason not to port over this small optimization.

Also updated some missed packages.lock.json files.

With these changes, I confirmed the end-to-end tests pass.

Azure IoT Edge PR checklist:

This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines and Best Practices

• I have read the contribution guidelines.
• Title of the pull request is clear and informative.
• Description of the pull request includes a concise summary of the enhancement or bug fix.

Testing Guidelines

• Pull request includes test coverage for the included changes.
• Description of the pull request includes
  • concise summary of tests added/modified
  • local testing done.