Clean up of WebProfiler Controller classes:

Added missing "@throws" PHPdoc comments in controllers
Updated deprecated reference to Symfony\Component\HttpKernel\Debug\ExceptionHandler to use Symfony\Component\Debug\ExceptionHandler instead
minor #9359 Clean up of WebProfiler Controller classes (caponica)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #9359).

Discussion
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Clean up of WebProfiler Controller classes

 - Added missing "@throws" PHPdoc comments in controllers
 - Updated deprecated reference to Symfony\Component\HttpKernel\Debug\ExceptionHandler to use Symfony\Component\Debug\ExceptionHandler instead

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no

Commits
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592b831 Clean up of WebProfiler Controller classes: