Clean up PHPStan configuration

[szepeviktor]

All Submissions:

• [x] Have you followed the plugin Contributing guideline?
• [x] Does your code follow the WordPress' coding standards?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Clean up PHPStan configuration.

[szepeviktor]

My biggest concern was removing %rootDir%/../../php-stubs/wordpress-stubs/wordpress-stubs.php from the bootstrapFiles or is PHPStan able to autoload these?

Hello! The package szepeviktor/phpstan-wordpress loads WP core stubs. https://github.com/szepeviktor/phpstan-wordpress/blob/c9fb3dc5e0a964845f6124a9c4394987749c657b/extension.neon#L93-L95

I may have introduced failures. Fixing now ...

[szepeviktor]

I hope you like 47 lines of deletion :)