Add t.Parallel() to java tests

Speeds up go test ./java from 32 seconds to 9 seconds.

Test: go test ./java
Change-Id: I4c6640e787c0744c6dfda03b7382839b452e24cf
diff --git a/java/aar_test.go b/java/aar_test.go
index aa4f0af..3ac228d 100644
--- a/java/aar_test.go
+++ b/java/aar_test.go
@@ -21,6 +21,7 @@
 )
 
 func TestAarImportProducesJniPackages(t *testing.T) {
+	t.Parallel()
 	ctx := android.GroupFixturePreparers(
 		PrepareForTestWithJavaDefaultModules,
 	).RunTestWithBp(t, `
@@ -50,6 +51,7 @@
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
 			appMod := ctx.Module(tc.name, "android_common")
 			appTestMod := ctx.ModuleForTests(tc.name, "android_common")
 
@@ -84,6 +86,7 @@
 }
 
 func TestLibraryFlagsPackages(t *testing.T) {
+	t.Parallel()
 	result := android.GroupFixturePreparers(
 		prepareForJavaTest,
 	).RunTestWithBp(t, `
@@ -133,6 +136,7 @@
 }
 
 func TestAndroidLibraryOutputFilesRel(t *testing.T) {
+	t.Parallel()
 	result := android.GroupFixturePreparers(
 		PrepareForTestWithJavaDefaultModules,
 	).RunTestWithBp(t, `