Merge #12076: qa: Use node.datadir instead of tmpdir in test framework

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

test/functional/test_framework/test_node.py

@@ -44,9 +44,9 @@ class TestNode():
     To make things easier for the test writer, any unrecognised messages will
     be dispatched to the RPC connection."""
 
-    def __init__(self, i, dirname, rpchost, timewait, binary, stderr, mocktime, coverage_dir, extra_conf=None, extra_args=None, use_cli=False):
+    def __init__(self, i, datadir, rpchost, timewait, binary, stderr, mocktime, coverage_dir, extra_conf=None, extra_args=None, use_cli=False):
         self.index = i
-        self.datadir = os.path.join(dirname, "node" + str(i))
+        self.datadir = datadir
         self.rpchost = rpchost
         if timewait:
             self.rpc_timeout = timewait
@@ -60,7 +60,7 @@ class TestNode():
         self.stderr = stderr
         self.coverage_dir = coverage_dir
         if extra_conf != None:
-            append_config(dirname, i, extra_conf)
+            append_config(datadir, extra_conf)
         # Most callers will just need to add extra args to the standard list below.
         # For those callers that need more flexibility, they can just set the args property directly.
         # Note that common args are set in the config file (see initialize_datadir)