Fix backport branch deletion on merge

[kotwanikunal]

Description

• Fixes backport branch deletion

Related Issues

Resolves #2128

Check List

• [ ] ~New functionality includes testing.~
• [ ] ~New functionality has been documented.~
• [ ] ~API changes companion pull request created.~
• [x] Commits are signed per the DCO using --signoff.
• [ ] ~Public documentation issue/PR created.~

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[navneet1v]

@kotwanikunal can you provide the testing details?

[kotwanikunal]

@kotwanikunal can you provide the testing details?

Sample Run: https://github.com/kotwanikunal/k-NN/actions/runs/11718170042/job/32639030059 GHA delete confirmation: https://github.com/kotwanikunal/k-NN/pull/3