Fix A/B test winner 500 error

[kuzmany]

Please be sure you are submitting this against the staging branch.

Q	A
Bug fix?
New feature?
Automated tests included?
Related user documentation PR URL
Related developer documentation PR URL
Issues addressed (#s or URLs)	#8853
BC breaks?
Deprecations?

Description:

I created an email which had an AB variant and ran the test. When I clicked to determine which one would become the winner a 500 error was thrown.

Steps to reproduce

1. Create email with a/b test variant
2. Run the test
3. Click on the trophy to decide the winner and accept the warning
4. Notice the 500 error

Log errors

[2020-05-30 14:02:14] mautic.CRITICAL: Uncaught PHP Exception InvalidArgumentException: "The _controller value "MauticEmailBundle:Page:view" maps to a "Mautic\EmailBundle\Controller\PageController" class, but this class was not found. Create this class or check the spelling of the class and its namespace." at /Users/ruth.cheesley/Sites/local.mautic3/vendor/symfony/framework-bundle/Controller/ControllerNameParser.php line 90 {"exception":"[object] (InvalidArgumentException(code: 0): The _controller value "MauticEmailBundle:Page:view" maps to a "Mautic\EmailBundle\Controller\PageController" class, but this class was not found. Create this class or check the spelling of the class and its namespace. at /Users/ruth.cheesley/Sites/local.mautic3/vendor/symfony/framework-bundle/Controller/ControllerNameParser.php:90)"} []

Steps to test this PR:

1. Load up this PR

List deprecations along with the new alternative:

List backwards compatibility breaks:

[RCheesley]

Tested and bug is resolved, thanks @kuzmany !

[npracht]

Good job 😎