Java test code clean-up

Remove unused parameters and make testJava return the config.

Test: Ran all java tests.
Change-Id: Iaa123f3fd93188e2f55452b887e1d340429cc710
diff --git a/java/plugin_test.go b/java/plugin_test.go
index d1aef2c..c7913d3 100644
--- a/java/plugin_test.go
+++ b/java/plugin_test.go
@@ -20,7 +20,7 @@
 )
 
 func TestNoPlugin(t *testing.T) {
-	ctx := testJava(t, `
+	ctx, _ := testJava(t, `
 		java_library {
 			name: "foo",
 			srcs: ["a.java"],
@@ -44,7 +44,7 @@
 }
 
 func TestPlugin(t *testing.T) {
-	ctx := testJava(t, `
+	ctx, _ := testJava(t, `
 		java_library {
 			name: "foo",
 			srcs: ["a.java"],
@@ -83,7 +83,7 @@
 }
 
 func TestPluginGeneratesApi(t *testing.T) {
-	ctx := testJava(t, `
+	ctx, _ := testJava(t, `
 		java_library {
 			name: "foo",
 			srcs: ["a.java"],