Use filegroups for test-{base,mock,runner} srcs

This allows soong to infer the package of the given srcs, which in turns
make it able to filter the inputs to metalava to exclude unwanted
packages.

This is part of a larger topic of changes intended to remove undesired
classes from the public documentation.

Bug: 187386774
Test: m
Change-Id: I8196c306b743ce6ca8a6452d212f3d7c0b5b2b82
diff --git a/ApiDocs.bp b/ApiDocs.bp
index c6a70d9..707b8c5 100644
--- a/ApiDocs.bp
+++ b/ApiDocs.bp
@@ -89,9 +89,9 @@
         ":updatable-media-srcs",
 
         // No longer part of the stubs, but are included in the docs.
-        "test-base/src/**/*.java",
-        "test-mock/src/**/*.java",
-        "test-runner/src/**/*.java",
+        ":android-test-base-sources",
+        ":android-test-mock-sources",
+        ":android-test-runner-sources",
     ],
     libs: framework_docs_only_libs,
     create_doc_stubs: true,