fix: update per_billed value in Purchase Receipt while creating Debit Note (backport #43977)

[mergify]

Issue:
per_billed value is always 100 for partial Debit Notes

ref: 22656

Before:
partial_return_debit_note_before.webm

After:
partial_return_debit_note_after.webm

backport needed for v14 and v15

---

This is an automatic backport of pull request #43977 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 494fd7c has failed:

On branch mergify/bp/version-14-hotfix/pr-43977
Your branch is up to date with 'origin/version-14-hotfix'.

You are currently cherry-picking commit 494fd7ceea.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   erpnext/stock/doctype/purchase_receipt/purchase_receipt.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[ruthra-kumar]

Depends on #44128

[frappe-pr-bot]

🎉 This PR is included in version 14.76.0 🎉

The release is available on GitHub release

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