Add UnsupportedAppUsage to java_aconfig_library dependency

Generated flag requires UnsupportedAppUsage annotation to expose the
flag to CTS tests.

Bug: 301272559
Test: presubit
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:5e2c96a93b4c16b224c090570a10697400a42c0a)
Merged-In: I90c87596ca80766ece429ddee1b45723b01d2760
Change-Id: I90c87596ca80766ece429ddee1b45723b01d2760
diff --git a/java/testing.go b/java/testing.go
index 98bea7f..0b7e685 100644
--- a/java/testing.go
+++ b/java/testing.go
@@ -410,6 +410,7 @@
 		"stub-annotations",
 
 		"aconfig-annotations-lib",
+		"unsupportedappusage",
 	}
 
 	for _, extra := range extraModules {