Enable slow tests on the internal bot

Bug: 139921800
Change-Id: I2cb02196d351399ef2097eb03b61e1f901c18454

tools/internal_test.py

diff --git a/tools/internal_test.py b/tools/internal_test.py
index 7730817..311b610 100755
--- a/tools/internal_test.py
+++ b/tools/internal_test.py
@@ -57,7 +57,7 @@
 
 TEST_COMMANDS = [
     # Run test.py internal testing.
-    ['tools/test.py', '--only_internal'],
+    ['tools/test.py', '--only_internal', '--slow_tests'],
     # Ensure that all internal apps compile.
     ['tools/run_on_app.py', '--ignore-java-version','--run-all', '--out=out']
 ]