Improve java_sdk_library handling of test_current

When building a library against sdk_version: system_current it uses the
system stubs of any java_sdk_library that it references. Previously,
when building against sdk_version: test_current this used the public
stubs of any java_sdk_library. This change causes it to use the
test stubs instead to be consistent with the handling of system and
public.

Bug: 148080325
Test: updated the test
      ran m nothing which failed as expected
	  fixed the code
	  ran m nothing again which succeeded
Change-Id: I58ec5bd243701c5a5c75664e2bb615ce7b2f2441

java/java_test.go

@@ -1043,6 +1043,12 @@ func TestJavaSdkLibrary(t *testing.T) {
 		    libs: ["baz"],
 		    sdk_version: "system_current",
 		}
+		java_library {
+			name: "baz-test",
+			srcs: ["c.java"],
+			libs: ["foo"],
+			sdk_version: "test_current",
+		}
 		`)
 
 	// check the existence of the internal modules
@@ -1075,6 +1081,13 @@ func TestJavaSdkLibrary(t *testing.T) {
 			"foo.stubs.jar")
 	}
 
+	bazTestJavac := ctx.ModuleForTests("baz-test", "android_common").Rule("javac")
+	// tests if baz-test is actually linked to the test stubs lib
+	if !strings.Contains(bazTestJavac.Args["classpath"], "foo.stubs.test.jar") {
+		t.Errorf("baz-test javac classpath %v does not contain %q", bazTestJavac.Args["classpath"],
+			"foo.stubs.test.jar")
+	}
+
 	// test if baz has exported SDK lib names foo and bar to qux
 	qux := ctx.ModuleForTests("qux", "android_common")
 	if quxLib, ok := qux.Module().(*Library); ok {