minor #3936 Remove usage of isset before array_key_exists as performa… #1037

Job	Run time
PHP 8.2	20s
PHP 8.3	11s
Integration tests with PHP 8.2	53s
extra/cache-extra with PHP 8.2	13s
extra/cssinliner-extra with PHP 8.2	25s
extra/html-extra with PHP 8.2	12s
extra/inky-extra with PHP 8.2	12s
extra/intl-extra with PHP 8.2	14s
extra/markdown-extra with PHP 8.2	15s
extra/string-extra with PHP 8.2	14s
extra/twig-extra-bundle with PHP 8.2	16s
extra/cache-extra with PHP 8.3	13s
extra/cssinliner-extra with PHP 8.3	14s
extra/html-extra with PHP 8.3	11s
extra/inky-extra with PHP 8.3	12s
extra/intl-extra with PHP 8.3	19s
extra/markdown-extra with PHP 8.3	13s
extra/string-extra with PHP 8.3	20s
extra/twig-extra-bundle with PHP 8.3	22s
	5m 29s

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