Revert "Use D8 by default for android_test"

This reverts commit 02edc1004757f6d6d5c2e2a93f1e8656ae2435cf.

Reason for revert: Breaks test_suites_x86_64_coverage

Bug: 233421462
Change-Id: I7b04d3fd7802be0f271ea3c29ef25e3d08ab1389
diff --git a/java/app.go b/java/app.go
index 8c5933a..768d9e9 100755
--- a/java/app.go
+++ b/java/app.go
@@ -1017,7 +1017,7 @@
 func AndroidTestFactory() android.Module {
 	module := &AndroidTest{}
 
-	module.Module.dexProperties.Optimize.EnabledByDefault = false
+	module.Module.dexProperties.Optimize.EnabledByDefault = true
 
 	module.Module.properties.Instrument = true
 	module.Module.properties.Supports_static_instrumentation = true
@@ -1071,7 +1071,6 @@
 func AndroidTestHelperAppFactory() android.Module {
 	module := &AndroidTestHelperApp{}
 
-	// TODO(b/192032291): Disable by default after auditing downstream usage.
 	module.Module.dexProperties.Optimize.EnabledByDefault = true
 
 	module.Module.properties.Installable = proptools.BoolPtr(true)