Add deprecation note of MI access mode in csi-secrets-store-identity-access.md

[JoeyC-Dev]

Proposed change:

1. Add deprecation note to alert user that both managed identity access modes will be deprecated.
2. Change "user identity" to "user-assigned managed identity".

Supporting point:

• Deprecating User-assigned and System-assigned managed identity access modes Azure/secrets-store-csi-driver-provider-azure#837
  In the "deprecation plan", the announcement also mentioned that user-assigned and system-assigned managed identity access modes will be removed from doc.
  Users should be warned about this.

[prmerger-automator]

@JoeyC-Dev : Thanks for your contribution! The author(s) have been notified to review your proposed change.

[Court72]

@Nickomang

Can you review the proposed changes?

When the changes are ready for publication, add a #sign-off comment to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
@MicrosoftDocs/public-repo-pr-review-team

[learn-build-service-prod]

Learn Build status updates of commit 32c1eec:

✅ Validation status: passed

File	Status	Preview URL	Details
articles/aks/csi-secrets-store-identity-access.md	✅Succeeded

For more details, please refer to the build report.

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[PMEds28]

@Nickomang

Can you review this old PR and determine whether it needs to be closed or merged?

IMPORTANT: When the changes are ready for publication, add a #sign-off comment to signal that the PR is ready for the review team to merge. If the changes no longer apply, add an explanation and a #please-close comment to close the PR.

@MicrosoftDocs/public-repo-pr-review-team

[JillGrant615]

@JoeyC-Dev @Nickomang

Can you review this old PR and determine whether it needs to be closed or merged?

IMPORTANT: When the changes are ready for publication, add a #sign-off comment to signal that the PR is ready for the review team to merge. If the changes no longer apply, add an explanation and a #please-close comment to close the PR.

@MicrosoftDocs/public-repo-pr-review-team

[Nickomang]

Thanks for the feedback, @JoeyC-Dev! At this time, we're in the process of migrating this content to a new repository. I'll be closing this pull request for now, but I will follow up over the next few weeks with details on how you can re-open the changes against the new repo. We appreciate the patience as we finalize the migration.

#please-close

[Nickomang]

@JoeyC-Dev, We’re happy to share that contributions to AKS are once again possible at MicrosoftDocs/azure-aks-docs. We appreciated your patience during this migration.

To re-open your contribution, follow these steps:

1. Fork and clone the new repository MicrosoftDocs/azure-aks-docs.
2. Create a new branch in your fork.
3. Copy the raw markdown for each file touched in your original PR.
4. In your fork’s new branch, paste each markdown file.
5. Commit the changes and open a new PR against the MicrosoftDocs/azure-aks-docs main branch.