Remove test BUCK configuration for cxxcomponents

Summary:
This diff removes the 'test' BUCK configuration for cxxcomponents, the goal of the diff is to fix a sandcastle issue:
https://www.internalfb.com/intern/sandcastle/log/?instance_id=36028797791859555&step_id=36028805144809956&step_index=6&name=Run%20arc%20focus-android

build-break
overriding_review_checks_triggers_an_audit_and_retroactive_review
Oncall Short Name: react_native

changelog: [internal] internal

Differential Revision: D39589523

fbshipit-source-id: 9cb6ab1e8a5929e7d288771f2f980db00a5a4adb

Author: mdvacca

ReactAndroid/src/main/jni/react/cxxcomponents/BUCK

@@ -34,7 +34,6 @@ rn_xplat_cxx_library(
         "-DWITH_FBSYSTRACE=1",
     ],
     soname = "libcxxcomponents.$(ext)",
-    tests = [":tests"],
     visibility = ["PUBLIC"],
     deps = [
         "//third-party/glog:glog",