Replacing deprecated at() calls in unit tests

[escopecz]

Q	A
Branch?	"features"
Bug fix?	yes/no
New feature?	yes/no
Deprecations?	no
BC breaks?	no
Automated tests included?	yes
Related user documentation PR URL	/
Related developer documentation PR URL	/
Issue(s) addressed	https://mautic.atlassian.net/browse/TPROD-161

Description:

After the PHPUNIT upgrade our test reports were showing warning in many tests. This PR refactors the tests that were using at() method to something else to get cleaner test reports.

Steps to test this PR:

1. There was no change in the production code. So just check the GitHub Actions phpunit report.

[codecov]

Codecov Report

Merging #9835 (2e7770e) into features (c3e2676) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@              Coverage Diff               @@
##             features    #9835      +/-   ##
==============================================
+ Coverage       39.64%   39.66%   +0.02%     
  Complexity      33978    33978              
==============================================
  Files            1989     1989              
  Lines          105730   105731       +1     
==============================================
+ Hits            41913    41943      +30     
+ Misses          63817    63788      -29     

Impacted Files	Coverage Δ	Complexity Δ
...Bundle/EventListener/DetermineWinnerSubscriber.php	86.44% <100.00%> (ø)	21.00 <1.00> (ø)
...DashboardBundle/Controller/DashboardController.php	32.82% <100.00%> (+0.25%)	60.00 <0.00> (ø)
...Bundle/EventListener/DetermineWinnerSubscriber.php	80.90% <100.00%> (ø)	32.00 <1.00> (ø)
...ce/DeviceTrackingService/DeviceTrackingService.php	88.13% <100.00%> (ø)	18.00 <5.00> (ø)
...les/EmailBundle/EventListener/ReportSubscriber.php	33.81% <0.00%> (+0.29%)	49.00% <0.00%> (ø%)
...eadBundle/EventListener/ReportUtmTagSubscriber.php	92.85% <0.00%> (+3.57%)	9.00% <0.00%> (ø%)
app/bundles/FormBundle/Helper/FormUploader.php	60.81% <0.00%> (+13.51%)	24.00% <0.00%> (ø%)
app/bundles/CoreBundle/Helper/FilePathResolver.php	100.00% <0.00%> (+13.51%)	14.00% <0.00%> (ø%)
app/bundles/FormBundle/Crate/FileFieldCrate.php	100.00% <0.00%> (+57.14%)	3.00% <0.00%> (ø%)
app/bundles/FormBundle/Crate/UploadFileCrate.php	83.33% <0.00%> (+66.66%)	6.00% <0.00%> (ø%)

[dennisameling]

John, I'm speechless. This is incredible and impressive. Thank you SO much for working on this! Highly appreciated 🧙🏼 🚀