[BUGFIX] Fix frontend unit tests if executed standalone

* Unit tests are allowed for CLI anyway
* Remove allow all in data provider

The latter implicitly caused a global allow, as PHPUint parses
all data providers before any test is run, thus setting globals there
will cause them to be preserved (and restored when backup globals is true).

Releases: 6.2, 6.1, 6.0
Resolves: #59343
Change-Id: I646294bb472027e22d6edc0622068698fe9a88fc
Reviewed-on: https://review.typo3.org/30563
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel