[Dep] Ignore unknown class error on build/config/config-downgrade.php on shipmonk/composer-dependency-analyser to 1.8.4 #31494

Job	Run time
Composer Validate	23s
Preload php-parser Order	33s
Help and Version	25s
Run with Space in Directory	24s
Active Classes	21s
PHPStan	1m 30s
Commented Code	18s
Compatible PHPStan versions	20s
Finalize classes	33s
Check before/after test fixture on no-changes	19s
PHP Linter	31s
Check no "*.php" files in rules Fixture directory	24s
Detect composer dependency issues	17s
Check fixture classes are different to nodes	25s
	6m 43s

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