Automatically call TestingBuildParams.RelativeToTop()

Fixes the few tests that break due to this and which cannot easily be
separated into their own changes.

Bug: 183650682
Test: m nothing
Change-Id: Ia2f31213a1f114a78e66a81d89279ecde9f4c465
diff --git a/apex/apex_test.go b/apex/apex_test.go
index 5476fe8..11b23c6 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -5066,7 +5066,7 @@
 	}
 	// JNI libraries including transitive deps are
 	for _, jni := range []string{"libjni", "libfoo"} {
-		jniOutput := ctx.ModuleForTests(jni, "android_arm64_armv8-a_sdk_shared_apex10000").Module().(*cc.Module).OutputFile()
+		jniOutput := ctx.ModuleForTests(jni, "android_arm64_armv8-a_sdk_shared_apex10000").Module().(*cc.Module).OutputFile().RelativeToPath()
 		// ... embedded inside APK (jnilibs.zip)
 		ensureListContains(t, appZipRule.Implicits.Strings(), jniOutput.String())
 		// ... and not directly inside the APEX