lightning: fix "context cancel" overwrites the real error (#44734)

[ti-chi-bot]

This is an automated cherry-pick of #44734

What problem does this PR solve?

Issue Number: close #44733

Problem Summary:

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: D3Hunter, lance6716

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-06-29 09:03:41.778835443 +0000 UTC m=+871187.180085877: ☑️ agreed by lance6716.
• 2023-06-29 09:04:37.604049854 +0000 UTC m=+871243.005300302: ☑️ agreed by D3Hunter.

[purelind]

/test all

[tiprow]

@purelind: No presubmit jobs available for pingcap/[email protected]

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/test all

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