bug #29543 [Cache] Don't erase processed redis dsn (chalasr)

This PR was merged into the 4.2 branch.

Discussion
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[Cache] Don't erase processed redis dsn

| Q             | A
| ------------- | ---
| Branch?       | 4.2
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Commits
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7b2a337f7c [Cache] Fix dsn parsing

src/Symfony/Component/Cache/Traits/RedisTrait.php

@@ -96,7 +96,7 @@ trait RedisTrait
             return 'file:'.($m[1] ?? '');
         }, $dsn);
 
-        if (false === $params = parse_url($dsn)) {
+        if (false === $params = parse_url($params)) {
             throw new InvalidArgumentException(sprintf('Invalid Redis DSN: %s', $dsn));
         }