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/bts_osmotrx.py b/src/osmo_gsm_tester/bts_osmotrx.py
index c8fa594..46daf71 100644
--- a/src/osmo_gsm_tester/bts_osmotrx.py
+++ b/src/osmo_gsm_tester/bts_osmotrx.py
@@ -51,7 +51,7 @@
         self.suite_run.poll()
 
         self.log('Starting to connect to', self.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()
 
         self.inst = util.Dir(os.path.abspath(self.suite_run.trial.get_inst(OsmoBtsTrx.BIN_BTS_TRX)))