Force r8 even on eng for InternalAnnotationsTests

Bug: 405255922
Bug: 374975543
Test: manual, TH
Change-Id: I2621a4f125b5e569d528c68e39079827b2083449
diff --git a/javatests/com/android/internal/annotations/Android.bp b/javatests/com/android/internal/annotations/Android.bp
index 26d2bd1..86d2e21 100644
--- a/javatests/com/android/internal/annotations/Android.bp
+++ b/javatests/com/android/internal/annotations/Android.bp
@@ -41,6 +41,7 @@
     // code paths and their interop with annotations.
     optimize: {
         enabled: true,
+        enabled_on_eng: true,
         optimize: true,
         shrink: true,
         proguard_flags_files: ["proguard.flags"],