[fix](cloud) avoid false tablet diagnosis alarms in cloud mode (#60805)

[deardeng]

pick from #60805
Problem

SHOW TABLET DIAGNOSIS reports local-storage style errors in cloud (storage-compute separated) deployments. In cloud mode, replica version in FE is not a reliable per-backend data freshness signal, and backend disk pressure does not directly represent object-storage write availability.

Root cause

Diagnoser applied the same checks for both local and cloud modes:

• ReplicaBackendStatus always evaluated be.diskExceedLimit()

• ReplicaVersionStatus always required replica.version == partition visible version (and checked lastFailedVersion)

These checks are valid for local replicas but can produce false positives in cloud mode.

Change

• Added cloud-mode guard via Config.isCloudMode() in Diagnoser.

• In cloud mode, skip disk-exceed-limit check when building ReplicaBackendStatus.

• In cloud mode, skip replica-version equality and last-failed-version checks when building ReplicaVersionStatus.

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[deardeng]

run buildall

[hello-stephen]

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[hello-stephen]

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