Revert "Force r8 even on eng for InternalAnnotationsTests"

This reverts commit dc43268aff3db0e694fceaff69fb5d67f56b1d40.

Reason for revert: Droidmonitor created revert due to b/405397520. 

Change-Id: I57f3f23cdded5a0802143fcefd5d1bee2a74ffc3
diff --git a/javatests/com/android/internal/annotations/Android.bp b/javatests/com/android/internal/annotations/Android.bp
index 86d2e21..26d2bd1 100644
--- a/javatests/com/android/internal/annotations/Android.bp
+++ b/javatests/com/android/internal/annotations/Android.bp
@@ -41,7 +41,6 @@
     // code paths and their interop with annotations.
     optimize: {
         enabled: true,
-        enabled_on_eng: true,
         optimize: true,
         shrink: true,
         proguard_flags_files: ["proguard.flags"],