Using proper keep rule in testing proguard config

testing/android/proguard_for_test.flags

Index: testing/android/proguard_for_test.flags
diff --git a/testing/android/proguard_for_test.flags b/testing/android/proguard_for_test.flags
index a0f074a9bf647aa41be51f7ca5e7d699abf95598..3326074db6ab3d562af70be4951741d57bab9b33 100644
--- a/testing/android/proguard_for_test.flags
+++ b/testing/android/proguard_for_test.flags
@@ -23,6 +23,6 @@
 # then makes our calls to them use the implementation that we find in our .dex
 # file, which is broken. We need to rely on these calls resolving to the
 # system's implementation. See crbug.com/488192#c36.
--keep class org.apache.** {
+-keepnames class org.apache.** {
   *;
 }