fix: use native PHP truthiness for condition evaluation in when()/whenNot()

[michalsn]

Description
This PR fixes a bug where the when() and whenNot() methods did not treat certain falsy values like 0, '0', null, and empty arrays consistently with native PHP conditionals.

The condition checks are now explicitly cast to boolean using (bool), ensuring consistent and expected behavior across all falsy and truthy values.

Fixes #9575

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[michalsn]

Thank you @lonnieezell and @paulbalandan