Minor fix for registry CLI LIST command

[MilesHolland]

Description

Minor changes to the registry LIST operation's SDK code to use the autorest 'list' function instead of the 'list_by_subscription' function, which although preferrable, doesn't have an implemented backend yet.

All SDK Contribution checklist:

• [x] The pull request does not introduce [breaking changes]
• [x] CHANGELOG is updated for new features, bug fixes or other significant changes.
• [x] I have read the contribution guidelines.

General Guidelines and Best Practices

• [x] Title of the pull request is clear and informative.
• [x] There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• [ ] Pull request includes test coverage for the included changes.

e2e Test coverage for registry operations is dependent on a few more other PRs, and is out-of-scope of a minor repo sync/fix PR.

[azure-sdk]

API change check

APIView has identified API level changes in this PR and created following API reviews.

azure-ai-ml