Fix Issue with intermediate parents status

[jorgemd24]

Changes proposed in this Pull Request:

Follow-up of #2257.

Now that we're calculating product statuses in batches, it's possible for variations from the same parents to come in different batches. For example:

Batch 1: Variable 1 - Parent ID 1 - DISAPPROVED
Batch 2: Variable 2 - Parent ID 1 - APPROVED

This could impact the total count because variable products are grouped by their parents. So, in the previous example, we should only count 1 DISAPPROVED product instead of 1 DISAPPROVED + 1 APPROVED.

This PR addresses the issue by storing the latest status from the parent product, ensuring it can be used for the total calculation.

Detailed test instructions:

1. It's a bit of a tricky situation to test, so I mainly relied on the Unit Tests to simulate the scenario. However, you can create batches of 1, each with a parent product having different variables, and check if the total count is correct. To do so identify a variable product in your store, and get a couple of variable ids with the same parent id.
2. Check that those variables are available in your Merchant Center.
3. Go to

   google-listings-and-ads/src/API/Google/Query/MerchantProductViewReportQuery.php

   Lines 22 to 28 in d7ecd99

   	public function __construct( array $args ) {
   	parent::__construct( 'ProductView' );
   	$this->set_initial_columns();
   	$this->handle_query_args( $args );
   	}

   and add the following line: $this->where( 'product_view.offer_id', ['gla_VARIABLE_ID_1', 'gla_VARIABLE_ID_2'], 'IN' );
4. Change the batch size to 1 in this line:

   google-listings-and-ads/src/API/Google/MerchantReport.php

   Line 68 in d7ecd99

   $batch_size = apply_filters( 'woocommerce_gla_product_view_report_page_size', 500 );

5. Call the following endpoint GET wc/gla/mc/product-statistics/refresh
6. You should get only one status.

Changelog entry

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6a9a0f9) 59.9% compared to head (d7ecd99) 60.0%.
Report is 11 commits behind head on feature/refactor-product-stats.

Additional details and impacted files

@@                       Coverage Diff                        @@
##             feature/refactor-product-stats   #2263   +/-   ##
================================================================
  Coverage                              59.9%   60.0%           
- Complexity                             4178    4181    +3     
================================================================
  Files                                   457     457           
  Lines                                 17708   17721   +13     
================================================================
+ Hits                                  10611   10627   +16     
+ Misses                                 7097    7094    -3     

Flag	Coverage Δ
php-unit-tests	60.0% <100.0%> (+<0.1%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/MerchantCenter/MerchantStatuses.php	52.1% <100.0%> (+2.1%)	⬆️

... and 1 file with indirect coverage changes

[ianlin]

Thanks for addressing the problem of status priority in different batches. I tested using a small set of products and the calculation looked great. 👍