hal_implementation_test: clear 'AOSP' error

Cuttlefish should only have AOSP HAL implementations. In the internal
TreeTop dashboard, the test failure is shown separately from the test
name. So, introducing this extra message to clarify the test failure
when it is by itself.

Bug: N/A
Test: build only
Change-Id: I506b02c16ca1211b4e26d3f461754d44827ce6dd
diff --git a/tests/hal/hal_implementation_test.cpp b/tests/hal/hal_implementation_test.cpp
index 471aebb..3674d15 100644
--- a/tests/hal/hal_implementation_test.cpp
+++ b/tests/hal/hal_implementation_test.cpp
@@ -190,7 +190,9 @@
 
 TEST(Hal, AllHidlInterfacesAreInAosp) {
     for (const FQName& name : allHidlManifestInterfaces()) {
-        EXPECT_TRUE(isAospHidlInterface(name)) << name.string();
+      EXPECT_TRUE(isAospHidlInterface(name))
+          << "This device should only have AOSP interfaces, not: "
+          << name.string();
     }
 }
 
@@ -248,7 +250,8 @@
 
 TEST(Hal, AllAidlInterfacesAreInAosp) {
     for (const std::string& name : allAidlManifestInterfaces()) {
-        EXPECT_TRUE(isAospAidlInterface(name)) << name;
+      EXPECT_TRUE(isAospAidlInterface(name))
+          << "This device should only have AOSP interfaces, not: " << name;
     }
 }