INT 2085: Optimize transaction backfill order search

[sethobey]

Context

Current BackfillTransactions:class observer uses SearchCriteria to retrieve orders within given date and store constraints, but does not consider whether the order is actually "syncable" before batching that order into a bulk operation. The consumer Backfill::class then determines whether or not we should sync the transaction. This means that potentially many unnecessary operations are created only to determine that the orders within should not be synced.

Description

This PR will now check within BackfillTransactions:class whether or not "force" option was enabled, and if force is not enabled, only syncable orders will be included in operations. While adding this functionality, BackfillTransactions.php was refactored, unit and integration tested.

Also corrects failing Transaction::class unit tests

Performance

The same total number of order-date comparisons will now be paid upfront instead spread across consumer processes, but there should be a net decrease in number of operations for the same request.

Testing

Automated Testing

• Adds Taxjar\SalesTax\Test\Unit\Observer\BackfillTransactionsTest.php
• Adds Taxjar\SalesTax\Test\Integration\Observer\BackfillTransactionsTest.php

Manual Testing

1. Enable Taxjar transaction sync
2. Create/invoice/ship an order (optionally create credit memo as well)
3. Observe order is synced with Taxjar
4. Trigger backfill transaction sync (not forced) with date range inclusive of order
5. Observe created order not included in any created operations
6. Trigger forced backfill transaction sync with date range inclusive of order
7. Observe created order is now included in created operations

Versions

• Magento 2.4
• Magento 2.3
• Magento 2.2
• Magento 2.1

• Magento Open Source (CE)
• Magento Commerce (EE)
• Magento B2B
• Magento Cloud

• PHP 7.x
• PHP 5.x

[dallendalton]

When running a backfill without force enab