[TASK] Replace prophecy in EXT:core/Tests/Unit/Mail/*

Resolves: #98809
Resolves: #98810
Resolves: #98811
Resolves: #98812
Releases: main
Change-Id: I043c797873be9df1ce1356fd4c3425bc0018673a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76567


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>