Use 'stem' to override APK name

When android_app.stem is set, use it as the APK name like other module
types.

Bug: 193504286
Test: m (soong test)
Change-Id: I4c95b77be382cff3cfecaf6ce38f99aed9f3238f
diff --git a/java/app.go b/java/app.go
index 1c69aeb..a319498 100755
--- a/java/app.go
+++ b/java/app.go
@@ -621,7 +621,7 @@
 	a.aapt.useEmbeddedDex = Bool(a.appProperties.Use_embedded_dex)
 
 	// Check if the install APK name needs to be overridden.
-	a.installApkName = ctx.DeviceConfig().OverridePackageNameFor(a.Name())
+	a.installApkName = ctx.DeviceConfig().OverridePackageNameFor(a.Stem())
 
 	if ctx.ModuleName() == "framework-res" {
 		// framework-res.apk is installed as system/framework/framework-res.apk
@@ -1006,6 +1006,7 @@
 	command := rule.Command().BuiltTool("test_config_fixer").Input(testConfig).Output(fixedConfig)
 	fixNeeded := false
 
+	// Auto-generated test config uses `ModuleName` as the APK name. So fix it if it is not the case.
 	if ctx.ModuleName() != a.installApkName {
 		fixNeeded = true
 		command.FlagWithArg("--test-file-name ", a.installApkName+".apk")