[Backport] 1190: CreateOrderBackendPartOneTest rework to support MSI reservation mechanism.

[mageprince]

Original Pull Request

#16153

Description

Add shipment step to CreateOrderBackendPartOneTest in order to support MSI reservation mechanism.

Standard magento behaviour - product quantity decreased immediately after place order, but with MSI quantity decreasing only after shipment created, as MSI introduces additional property for product as 'salable quantity'. And after order placement, 'salable quantity' decreasing, not quantity itself(more about reservation mechanism here). Quantity decreasing only after shipment creation. So, in order to pass CreateOrderBackendPartOneTest with MSI, additional step with shipment creation should be added into test before assertions.

Fixed Issues (if relevant)

1. Fix Functional Test Magento\Sales\Test\TestCase\CreateOrderBackendPartOneTest::test with data set "CreateOrderBackendTestVariation1_0" inventory#1190: Fix Functional Test Magento\Sales\Test\TestCase\CreateOrderBackendPartOneTest::test with data set "CreateOrderBackendTestVariation1_0"

Manual testing scenarios

1. None

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-engcom-team]

Hi @mageprince. Thank you for your contribution
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[sidolov]

Hi @mageprince , provided changes made especially for 2.3 release line to support MSI project and not applicable for 2.2 release line. I'm closing this PR as not relevant.