Remove --ignore-classes-on-classpath argument

This argument doesn't appear to alter the output.

Bug: 186197911
Test: diff metadata.zip, stubs.srcjar, annotations.zip before and after
Change-Id: I5147cf1f0658c78e5ab24952285c8fc1c036a55d
diff --git a/ApiDocs.bp b/ApiDocs.bp
index d3bef7f..5cbc78c 100644
--- a/ApiDocs.bp
+++ b/ApiDocs.bp
@@ -99,9 +99,7 @@
     arg_files: [
         "core/res/AndroidManifest.xml",
     ],
-    args: metalava_framework_docs_args +
-        // Needed for hidden libcore annotations for now.
-        " --ignore-classes-on-classpath ",
+    args: metalava_framework_docs_args,
     write_sdk_values: true,
 }
 
@@ -112,8 +110,6 @@
         "core/res/AndroidManifest.xml",
     ],
     args: metalava_framework_docs_args +
-        // Needed for hidden libcore annotations for now.
-        " --ignore-classes-on-classpath " +
         " --show-annotation android.annotation.SystemApi\\(client=android.annotation.SystemApi.Client.PRIVILEGED_APPS\\) ",
     write_sdk_values: true,
 }