fix: correct bank entry calculation with deductions and prevent multiple loan repayment deductions (backport #2347)

[mergify]

Introduced via #2283 & #2324 and loan flow.

Issue:

• When deductions were present, the bank entry calculation did not work as expected.
• total_loan_repayment was being subtracted multiple times for each salary detail, leading to an incorrect salary_slip_total in the bank entry.

Resolution:

• Adjusted the get_salary_slip_details function to ensure total_loan_repayment is fetched only once per unique salary slip.
• In the make_bank_entry function, we separated the total_loan_repayment deduction from the main loop, ensuring it’s only subtracted once per salary slip, after calculating the total of earnings and deductions.

  ---

  This is an automatic backport of pull request fix: correct bank entry calculation with deductions and prevent multiple loan repayment deductions #2347 done by Mergify.

[mergify]

Cherry-pick of 44cdcc7 has failed:

On branch mergify/bp/version-15-hotfix/pr-2347
Your branch is ahead of 'origin/version-15-hotfix' by 1 commit.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 44cdcc7df.
  (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:   hrms/payroll/doctype/payroll_entry/payroll_entry.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   hrms/payroll/doctype/payroll_entry/test_payroll_entry.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

[frappe-pr-bot]

🎉 This PR is included in version 15.34.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀