Fix file location of spree/line_item_action.rb

[mamhoff]

When this was moved to the correct gem, we failed to also move it to the right directory. This generates Zeitwerk errors.

[tvdeyen]

This should fix failing specs in https://github.com/solidusio/solidus_starter_frontend/pull/374

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.54%. Comparing base (8ff6267) to head (8710da9). Report is 4 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #5923 +/- ## ========================================== + Coverage 87.81% 89.54% +1.72% ========================================== Files 476 782 +306 Lines 11656 17988 +6332 ========================================== + Hits 10236 16107 +5871 - Misses 1420 1881 +461 ```

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[github-actions[bot]]

💚 All backports created successfully

Status	Branch	Result
✅	v4.4

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