ansible: docker: clean vfs storage leftovers

Docker is configured via ansible to use the overlay2 storage driver
since August 2020 (I20728d6017204c3978e23376baa89de6e91fed1e). Clean up
an unused vfs dir if it is present on the system, as it was the case on
build2-deb9build-ansible with a 190 GiB vfs dir.

Related: OS#5827
Change-Id: I58f3f4a26ad6fa4698d87475cefb6ab21e66b15a
1 file changed