Log debuggerd -j output when sampling memory use.

To get more logging around what GC has occurred over the course of the
test.

Test: atest -v system-memory-test
Bug: 111830582
Change-Id: I11827c78d73f3ddbf5e4e988c99abb96aebdc03a
diff --git a/tests/SystemMemoryTest/README.txt b/tests/SystemMemoryTest/README.txt
index de5042c..8ffca15 100644
--- a/tests/SystemMemoryTest/README.txt
+++ b/tests/SystemMemoryTest/README.txt
@@ -13,8 +13,7 @@
 
 You can manually run the test as follows:
 
-  make tradefed-all system-memory-test SystemMemoryTestDevice
-  tradefed.sh run commandAndExit template/local_min --template:map test=system-memory-test
+  atest -v system-memory-test
 
 This installs and runs the test on device. You can see the metrics in the
 tradefed output.