client/router: fix the incorrect deep copy method in QueryRegion

[JmPotato]

What problem does this PR solve?

Issue Number: ref #8690.

What is changed and how does it work?

Although #9055 identified the problem, the proposed fix is incorrect because the first request using the same region can still modify the data concurrently.
This PR resolves the issue by deep-copying the region from the response each time.

Check List

Tests

• Unit test
• Integration test
• Manual test

Before:

After:

Release note

None.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rleungx

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-02-14 07:34:12.330636457 +0000 UTC m=+601094.726858519: ☑️ agreed by rleungx.

[ti-chi-bot]

@JmPotato: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-integration-realcluster-test	33db286	link	true	/test pull-integration-realcluster-test

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