Cleanup of vertx-cache temporary directories

[rsvoboda]

Introduce enhancement to clean vertx-cache temporary directories

Highlighted during review of #15541 (review)

The previous approach was not deleting the directory either, but it is better to do the cleanup if we have created the directory.

We won't clean if it's a directory set by the user (because it would reuse it during the next execution, and so would allow avoiding copying files over).

[quarkus-bot]

/cc @gwenneg

[rsvoboda]

/cc @cescoffier

[cescoffier]

I did it as part of #15541.