br: optimizing retry-able function

[fengou1]

What problem does this PR solve?

Problem Summary:
Context Cancel is not retry-able. if gcs is temp unavailable, the backup will failure.

What is changed and how it works?

What's Changed:
if context cancel, do not retry
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 add a release note, or a 'None' if it is not needed.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• YuJuncen
• kennytm

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[fengou1]

/cc @Lanearth @kennytm @YuJuncen

[ti-chi-bot]

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[sre-bot]

Please follow PR Title Format:

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[sre-bot]

Please follow PR Title Format:

• pkg [, pkg2, pkg3]: what is changed

Or if the count of mainly changed packages are more than 3, use

• *: what is changed

After you have format title, you can leave a comment /run-check_title to recheck it

[kennytm]

/run-check_title

[fengou1]

/cc @Leavrth

[fengou1]

/run-check_dev_2

[CLAassistant]

All committers have signed the CLA.

[fengou1]

/run-check_dev_2

[fengou1]

/run-build

[fengou1]

/LGTM

[YuJuncen]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: b7ced92