Skip dexpreopting android_test_import modules

android_test_import modules should be labelled as tests so they are
not dexpreopted.

Bug: 155778135
Test: m CtsCorruptApkTests_Compressed_Q
Change-Id: I7baa5405d03df03920b01616b030ba77f882a77e

java/app.go

@@ -1398,6 +1398,8 @@ func AndroidTestImportFactory() android.Module {
 		module.processVariants(ctx)
 	})
 
+	module.dexpreopter.isTest = true
+
 	android.InitApexModule(module)
 	android.InitAndroidMultiTargetsArchModule(module, android.DeviceSupported, android.MultilibCommon)
 	android.InitDefaultableModule(module)