Add /prefetto/protos to DupFileTest exclusion

These files are included in both CTS and MTS test suites, and need to be
ignored.

Bug: 150954228
Test: make cts && cts-tradefed run cts-unit-tests
Change-Id: I3ff3a52c798f7089c3f8497b73eb7f24c1db3aa2
diff --git a/common/host-side/tradefed/tests/src/com/android/compatibility/common/tradefed/presubmit/DupFileTest.java b/common/host-side/tradefed/tests/src/com/android/compatibility/common/tradefed/presubmit/DupFileTest.java
index f50e59d..ce8d526 100644
--- a/common/host-side/tradefed/tests/src/com/android/compatibility/common/tradefed/presubmit/DupFileTest.java
+++ b/common/host-side/tradefed/tests/src/com/android/compatibility/common/tradefed/presubmit/DupFileTest.java
@@ -46,8 +46,13 @@
 
     // We ignore directories part of the common java and google packages.
     private static final String[] IGNORE_DIRS =
-            new String[] {"android/", "javax/annotation/", "com/google/protobuf/", "kotlin/"};
-
+            new String[] {
+                "android/",
+                "javax/annotation/",
+                "com/google/protobuf/",
+                "kotlin/",
+                "perfetto/protos/"
+            };
     // Temporarily exclude some Tradefed jar while we work on unbundling them.
     private static final Set<String> IGNORE_JARS = ImmutableSet.of("tradefed-test-framework.jar");