public static void printFile(File f, String content) throws IOException {
        OutputStream out = new FileOutputStream(f);
        out.write(content.getBytes());
        out.close();

    }
Updates the chains config, while the searcher configs are unchanged.
Verifies that a new searcher that was not in the old config is instantiated,
and that a searcher that has been removed from the configuration is not in the new registry.
container-search/src/test/java/com/yahoo/search/searchchain/config/test/SearchChainConfigurerTestCase.java