fix: contact duplication on converting lead to customer

[anupamvs]

Issue - #28910

Removed unused code.

[codecov]

Codecov Report

Merging #29353 (ebb9d8d) into develop (180f06d) will decrease coverage by 0.13%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop   #29353      +/-   ##
===========================================
- Coverage    58.03%   57.90%   -0.14%     
===========================================
  Files         1091     1091              
  Lines        67866    67835      -31     
===========================================
- Hits         39388    39281     -107     
- Misses       28478    28554      +76     

Impacted Files	Coverage Δ
erpnext/selling/doctype/customer/customer.py	69.96% <100.00%> (+4.85%)	⬆️
...ext/accounts/report/balance_sheet/balance_sheet.py	36.36% <0.00%> (-21.82%)	⬇️
...payroll/doctype/income_tax_slab/income_tax_slab.py	83.33% <0.00%> (-16.67%)	⬇️
...em_wise_sales_register/item_wise_sales_register.py	51.81% <0.00%> (-11.37%)	⬇️
...t/accounts/report/sales_register/sales_register.py	71.51% <0.00%> (-9.10%)	⬇️
...pnext/accounts/report/gross_profit/gross_profit.py	82.49% <0.00%> (-6.62%)	⬇️
...eport/item_variant_details/item_variant_details.py	84.33% <0.00%> (-3.62%)	⬇️
erpnext/stock/report/stock_ledger/stock_ledger.py	75.60% <0.00%> (-2.44%)	⬇️
...unts/report/purchase_register/purchase_register.py	71.23% <0.00%> (-2.06%)	⬇️
...xt/stock/report/stock_analytics/stock_analytics.py	91.08% <0.00%> (-1.99%)	⬇️
... and 20 more