Add instance discovery to 2.54.0 history notes

[jiasli]

Azure/azure-cli#27494 added a history note for instance discovery to Core: https://github.com/Azure/azure-cli/blob/dev/src/azure-cli-core/HISTORY.rst#2540

[Core] [PREVIEW] Support disabling instance discovery by running `az config set core.instance_discovery=false`

But currently the release pipeline doesn't include core changes, so we have to manually copy them (similar to #2815)

[learn-build-service-prod]

Learn Build status updates of commit 1273c99:

⚠️ Validation status: warnings

File	Status	Preview URL	Details
docs-ref-conceptual/release-notes-azure-cli.md	⚠️Warning	View	Details

docs-ref-conceptual/release-notes-azure-cli.md

• Line 832, Column 1: [Warning: duplicate-h2s - See documentation] Duplicate heading: 'H2 'April 25, 2023''. Each second level heading (H2) in an article must be unique.
• Line 840, Column 1: [Warning: duplicate-h2s - See documentation] Duplicate heading: 'H2 'April 25, 2023''. Each second level heading (H2) in an article must be unique.
• Line 1201, Column 1: [Warning: disallowed-heading - See documentation] Heading 'H3 'Feedback'' matches the text of a disallowed Docs template heading.
• Line 1793, Column 1: [Warning: disallowed-heading - See documentation] Heading 'H3 'Feedback'' matches the text of a disallowed Docs template heading.

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[dbradish-microsoft]

@jiasli, Can this PR be closed or merged?

[dbradish-microsoft]

@jiasli, This PR is almost 6 months old. Please move it back to Draft so it doesn't get closed in June 2024 as part of my PR cleanup process. Thank you.