Clear previous errors after completing sync

[mikkamp]

Changes proposed in this Pull Request:

This PR clears out previous sync errors if the synced countries are all contained within the set of target countries. Previously the length of the arrays needed to match as well. This is no longer the case since we don't sync each target country individually anymore.

The unit tests were updated to reflect the new behaviour.

Closes #2737

Detailed test instructions:

1. On a site where we completed onboarding (and use a live URL so we are allowed to sync)
2. During onboarding make sure to select multiple target countries
3. Create a product with no description (complete all other requirements such as product image and price)
4. Save the product with Sync and Show status to trigger the sync
5. Wait for Action Scheduler to complete sync
6. Edit the product and confirm the error has shown up after sync attempt
   
7. View the product issues in the Product Feed page and confirm that the issue is showing up there as well
8. Update the product to add a description and complete all requirements so it can sync
9. Wait for the product sync to complete
10. Edit the product and confirm the errors don't show up in the product
11. View the product issues in the Product Feed page and confirm that the issue is not showing up there either
12. Clear the product status cache to reload it (tool in connection test page)
13. View the product issues table again and confirm that the error is still not there

Changelog entry

• Fix - Clear previous errors after completing sync.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.0%. Comparing base (3b936b3) to head (8284510).
Report is 5 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##             develop   #2738     +/-   ##
===========================================
+ Coverage       66.3%   67.0%   +0.7%     
+ Complexity      4693    4692      -1     
===========================================
  Files            816     479    -337     
  Lines          24805   19612   -5193     
  Branches        1273       0   -1273     
===========================================
- Hits           16435   13136   -3299     
+ Misses          8197    6476   -1721     
+ Partials         173       0    -173     

Flag	Coverage Δ
js-unit-tests	?
php-unit-tests	67.0% <100.0%> (ø)

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

Files with missing lines	Coverage Δ
src/Product/ProductHelper.php	92.3% <100.0%> (ø)

... and 337 files with indirect coverage changes

[eason9487]

Thanks for the fix! Confirmed that after product issues are resolved and the product is synced, the corresponding issues on the product editor and the "Issues to resolve" table no longer appear. LGTM.