fix: set taxes and totals before validating subcontracting transaction (backport #3782)

[mergify]

Fixes: #3777

Summary by CodeRabbit

• Refactor

  • Tax initialization now runs earlier and only once, preventing duplicate calculations.

• Bug Fixes / Tests

  • total_taxes now shows 0.0 (not blank) for subcontracting orders with unregistered entities and for material receipt stock entries.

• Tests

  • Updated ITC-04 export expectations: adjusted an item's reported value from 0.0 to 200.0.

---

This is an automatic backport of pull request #3782 done by [Mergify](https://mergify.com).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.89%. Comparing base (8ca7140) to head (f28b5b0).
⚠️ Report is 42 commits behind head on version-15-hotfix.

Additional details and impacted files

@@                Coverage Diff                 @@
##           version-15-hotfix    #3960   +/-   ##
==================================================
  Coverage              59.89%   59.89%           
==================================================
  Files                    140      140           
  Lines                  14879    14879           
==================================================
  Hits                    8912     8912           
  Misses                  5967     5967           

Files with missing lines	Coverage Δ
.../gst_india/overrides/subcontracting_transaction.py	84.78% <100.00%> (ø)

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[india-compliance-bot]

🎉 This PR is included in version 15.25.5 🎉

The release is available on GitHub release

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