FlaggedApi: enable UnflaggedApi lint for public + system API

Bug: 297362755
Test: make checkapi
Change-Id: If7333ead86d9028ab0a1cc8f25fc534cb13a1858
diff --git a/api/StubLibraries.bp b/api/StubLibraries.bp
index e481fe9..c59a833 100644
--- a/api/StubLibraries.bp
+++ b/api/StubLibraries.bp
@@ -47,6 +47,7 @@
         api_lint: {
             enabled: true,
             new_since: ":android.api.public.latest",
+            baseline_file: ":non-updatable-lint-baseline.txt",
         },
     },
     dists: [
@@ -73,7 +74,8 @@
     "client=android.annotation.SystemApi.Client.PRIVILEGED_APPS" +
     "\\)"
 
-test = " --show-annotation android.annotation.TestApi"
+test = " --show-annotation android.annotation.TestApi" +
+    " --hide UnflaggedApi" // TODO(b/297362755): TestApi lint doesn't ignore existing APIs.
 
 module_libs = " --show-annotation android.annotation.SystemApi\\(" +
     "client=android.annotation.SystemApi.Client.MODULE_LIBRARIES" +