…tized logs processing

…in the sanitized logs processing (fancyweb)

This PR was merged into the 3.4 branch.

Discussion
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[HttpKernel][LoggerDataCollector] Prevent keys collisions in the sanitized logs processing

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | symfony/symfony#36159
| License       | MIT
| Doc PR        | -

`$sanitizedLogs` is used with numeric and "associative" keys. To prevent collisions when the message is a number, we can simply prepend all messages with a random letter (so we avoid a behavior refactor). It doesn't matter since they key is only used for the processing, it is dropped at the end.

Commits
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79fe888072 [HttpKernel][LoggerDataCollector] Prevent keys collisions in the sanitized logs processing

* 3.4:
  Fix wrong namespaces
  [Validator] Fixed calling getters before resolving groups
  [HttpKernel][LoggerDataCollector] Prevent keys collisions in the sanitized logs processing

* 3.4:
  Revert "[travis][appveyor] don't cache .phpunit"
  silence E_NOTICE triggered since PHP 7.4
  [Form] Removed legacy check in `ValidationListener`
  do not merge constraints within interfaces
  [Validator] Fixed default group for nested composite constraints

* 3.4:
  Tweak the code to avoid fabbot false positives