Fix Budget Recommendation data not populating on install

[mikkamp]

Changes proposed in this Pull Request:

This PR fixes an issue that was introduced in PHP 8.4 compatibility code.

The budget recommendation was covered by unit testing, although it used mocked data, so it didn't catch the testing of actually installing the database table. Since we have database tables available during unit testing I added two types of tests:

1. Trigger the DB install code to run with the unit test DB and confirm it doesn't generate any errors
2. Query from the DB tables with pre-populated data (which expects the install / population process to have completed)

Closes #2730

Detailed test instructions:

1. Install extension from scratch
2. Check the database table wp_gla_budget_recommendations is created and contains rows of imported data

Alternative way to test:

1. Drop / rename table wp_gla_budget_recommendations
2. Use this filter to force running the install code add_filter( 'woocommerce_gla_force_run_install', '__return_true' );
3. Ensure the DB table is recreated and populated

Changelog entry

• Fix - Budget Recommendation data not populating on install.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.6%. Comparing base (e849de8) to head (03be696).
Report is 5 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##             develop   #2732     +/-   ##
===========================================
+ Coverage       66.2%   66.6%   +0.4%     
  Complexity      4691    4691             
===========================================
  Files            479     479             
  Lines          19608   19608             
===========================================
+ Hits           12983   13064     +81     
+ Misses          6625    6544     -81     

Flag	Coverage Δ
php-unit-tests	66.6% <100.0%> (+0.4%)	⬆️

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

Files with missing lines	Coverage Δ
src/DB/Table/BudgetRecommendationTable.php	96.4% <100.0%> (+48.2%)	⬆️

... and 2 files with indirect coverage changes

[tomalec]

Thank you for such a quick fitx @mikkamp !
I reviewed the code & tested locally, LGTM