Groovy formatting with Spotless leaves a temporary directory

[baloo42]

Is your task related to a problem? Please describe

There is currently a bug in the spotless groovy formatter which affects this project:
Spotless leaves a temporary directory on each formatter execution.

diffplug/spotless#2019

Introduced with PR #6301

Describe the solution you'd like

All temporary directories are cleaned up after an execution.

Describe alternatives you've considered

No response

Additional context

First discussed here: #5979 (comment)

we can try and live with this for now. If it gets annoying we can disable.

[baloo42]

@manusa I created this just as a reminder, nothing urgent.