Since Vault become persistent, tests create vault files in a module high-level directory.
This directory is not ignored by git, which may lead to unwanted data in git repo,
and maybe some other unexpected things.
- introduce a working directory for nodes where all node files will be stored.
- add workdir to gitignore
We can use Ignite-2 approach for now and improve later in a separate ticket if there are issues we want to resolve.