Add AppSearchCtsTests to visibility of the test utils.

This wasn't caught by presubmit but is causing build breakages.

Bug: 170997047
Bug: 162450968
Bug: 175661706
Test: m -j CtsAppSearchTestCases

Change-Id: Iba50493c1ad0f2272efcad7591d6c942a7323f34
diff --git a/apex/appsearch/testing/Android.bp b/apex/appsearch/testing/Android.bp
index f742ffc..54d5039 100644
--- a/apex/appsearch/testing/Android.bp
+++ b/apex/appsearch/testing/Android.bp
@@ -21,4 +21,5 @@
         "guava",
         "truth-prebuilt",
     ],
+    visibility: ["//cts/tests/appsearch"],
 }