[BUGFIX] Make Extbase EnvironmentService a Singleton

EnvironmentService is a service and gets injected in different
classes, thus it has to be a Singleton.

Resolves: #57518
Releases: 6.2, 6.1
Change-Id: Ia8a3b8882be27c0f45569af818964036f0a9b16d
Reviewed-on: https://review.typo3.org/29042
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel