Implicitly nullable parameter declarations are deprecated in PHP 8.4:
https://php.watch/versions/8.4/implicitly-marking-parameter-type-nullable-deprecated

The proposed syntax was introduced in PHP 7.1.

This patch is a followup on top of D25814.

Refs T15935

• Try to view a task in the browser
• Try to run ./bin/auth recover on the CLI
• Try to browse projects in the browser
• Try to create a new project without a name in the browser