cubicweb-vcsfile #2887135 proper repo cache handling [open]

currently there is no proper removal of repository cache directories, which may lead to a lot of disk consumption (eg > 14000 repo_cache subdirectories reported on an instance).

We should: * have an operation that remove the cache directory in the repository creation transaction is rollbacked) * have an operation that remove the cache directory in the repository deletion transaction is commited)

prioritynormal
typebug
done in<not specified>
load0.500
load left0.500
closed by<not specified>