Use a subdir of run_dir for each test

Processes created have the scope of the test, so we should store
everything in a per-suite_run/per-test directory, otherwise everything
is stored in the same trial run_dir directory and it's really messy.

Change-Id: I06be2dd21710e14c1337d13b1fe6c2f68f037957
diff --git a/src/osmo_gsm_tester/osmo_bsc.py b/src/osmo_gsm_tester/osmo_bsc.py
index 5447118..efbda1f 100644
--- a/src/osmo_gsm_tester/osmo_bsc.py
+++ b/src/osmo_gsm_tester/osmo_bsc.py
@@ -39,7 +39,7 @@
 
     def start(self):
         self.log('Starting osmo-bsc')
-        self.run_dir = util.Dir(self.suite_run.trial.get_run_dir().new_dir(self.name()))
+        self.run_dir = util.Dir(self.suite_run.get_test_run_dir().new_dir(self.name()))
         self.configure()
 
         # NOTE: While OsmoMSC and OsmoBSC live in the same git repository, the