Add PHPUnit tests for AbstractPage circular parent validation and Man… #1498

Job	Run time
Behat (Symfony ^7.4) (PHP 8.5) (lowest dependencies)	4m 2s
PHPUnit (Symfony 7.4) (PHP 8.5)	1m 44s
PHPUnit (Symfony NEXT 8.2) (PHP 8.5)	42s
Behat (Symfony NEXT 8.2) (PHP 8.5)	4m 1s
PHP-CS-Fixer (PHP 8.5)	18s
PHPUnit (Symfony 8.1) (PHP 8.5)	53s
Behat (Symfony 7.4) (PHP 8.5)	4m 48s
Behat (Symfony 8.1) (PHP 8.5)	4m 24s
PHPUnit (Symfony ^7.4) (PHP 8.5) (lowest dependencies)	52s
	21m 44s

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