Improve PHP 8.4 test bootstrap compatibility

[digitalbase]

Summary

• modernize test project setup by syncing submodule URLs, switching submodules to HTTPS, and updating prepare_tests.sh for current Symfony task/composer behavior
• make installer and plugin bootstrap more resilient across Symfony variants used in test fixtures
• reduce PHP 8.4 deprecation noise in test harness bootstrap and fix explicit plugin path setup in sfPropelDatabaseTest

Context

This branch focuses on unblocking test execution under local PHP 8.4. It does not fully resolve all remaining legacy vendor/runtime incompatibilities yet (notably old Propel/Phing parser/runtime issues), but it moves the suite past several bootstrap/setup blockers.

Validation

• ran php test/bin/prove.php with local PHP 8.4 (/opt/homebrew/opt/php@8.4/bin/php)
• confirmed progression from hard bootstrap/setup failures to downstream legacy compatibility failures

[digitalbase]

Honestly i don't think this should be merged. Wanted to just preserve the state on the fixes it did getting ready for PHP8.4.

There are other issues in the propel/phing packages and we need to upgrade rock-symphony first too