fix: internal transfer GLE validation

[ankush]

While doing internal transfers if both accounts are the same a GLE is made with equal credit/debit, this fails validation while submitting the doc.

Soln: toggle credit to negative debit (like done in other transactions)

ps: check added test case for example

[codecov]

Codecov Report

Merging #31264 (dd58e3a) into develop (46e6c2c) will decrease coverage by 0.24%.
The diff coverage is n/a.

❗ Current head dd58e3a differs from pull request most recent head f572c20. Consider uploading reports for the commit f572c20 to get more accurate results

@@             Coverage Diff             @@
##           develop   #31264      +/-   ##
===========================================
- Coverage    63.75%   63.50%   -0.25%     
===========================================
  Files          984      986       +2     
  Lines        67724    67456     -268     
===========================================
- Hits         43179    42841     -338     
- Misses       24545    24615      +70     

Impacted Files	Coverage Δ
erpnext/controllers/stock_controller.py	91.64% <ø> (ø)
...ctype/cash_flow_mapper/default_cash_flow_mapper.py	0.00% <0.00%> (-100.00%)	⬇️
erpnext/setup/default_energy_point_rules.py	0.00% <0.00%> (-75.00%)	⬇️
erpnext/setup/default_success_action.py	0.00% <0.00%> (-62.50%)	⬇️
erpnext/regional/saudi_arabia/setup.py	0.00% <0.00%> (-28.13%)	⬇️
erpnext/regional/italy/setup.py	0.00% <0.00%> (-27.28%)	⬇️
erpnext/utilities/doctype/video/video.py	0.00% <0.00%> (-21.35%)	⬇️
erpnext/setup/install.py	0.00% <0.00%> (-20.77%)	⬇️
..._arabia/wizard/operations/setup_ksa_vat_setting.py	0.00% <0.00%> (-19.05%)	⬇️
erpnext/accounts/doctype/bank/bank.py	71.42% <0.00%> (-14.29%)	⬇️
... and 76 more

[deepeshgarg007]

@Mergifyio backport version-13-hotfix

[mergify]

backport version-13-hotfix

✅ Backports have been created

• #31413 fix: internal transfer GLE validation (backport #31264) has been created for branch version-13-hotfix