c8330d4 qa: Use node.datadir instead of tmpdir in test framework (MarcoFalke)
Pull request description:
Commit c53c9831ee introduced the utility function `get_datadir_path`, however not all places in the code use this util function. Using the util function everywhere makes it easier to review pull requests related to the datadir.
This commit replaces datadir path creation with the `datadir` member of `TestNode`, which itself uses `get_datadir_path`.
Tree-SHA512: c75707ab7149d732a6d56152a5813138a33459d3d07577b60b89f2a207c83b7663fac5f203593677c9892d1c23a5eba4bd45c5c4ababf040d720b437240fcddf
This change should make it easier for users to make complete backups of wallets
because they can now just back up the specified `-wallet=<path>` path directly,
instead of having to back up the specified path as well as the transaction log
directory (for incompletely flushed wallets).
Another advantage of this change is that if two wallets are located in the same
directory, they will now use their own BerkeleyDB environments instead using a
shared environment. Using a shared environment makes it difficult to manage and
back up wallets separately because transaction log files will contain a mix of
data from all wallets in the environment.
