Prevents an exception for DWC and focus requests that aren't tracked

[alanhartless]

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

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

Description:

There are some scenarios where DWC and focus endpoints are not tracked leading to an exception when Doctrine tries to save a stat. This is happening most on sites with multiple tracking code snippets embedded (another bug to deal with).

Steps to reproduce the bug:

1. Create dynamic web content -> turn campaign based off and add a filter that would match any contact (country != mars or something like that). Note the slot name you used.
2. Open a guest/incognito browser session
3. browse to your-mautic.com/dwc/slot (replace slot with the name used in step 1)
4. Note the exception
5. Go back to the logged in session and visit the same URL - notice the different exception

Steps to test this PR:

1. Repeat and no exception will be thrown
2. Repeat while logged into Mautic and no exception will be thrown

[alanhartless]

Our team has reviewed this and it's been in production for months now so marking as pending test confirmation

[kuzmany]

@alanhartless Can you resolve conflicts?