Avoid filling up AntPathMatcher cache

This change avoid use of AntPathMatcher to extract URI template
variables when the lookup path is used as the best matching pattern.

Issue: SPR-10803
(cherry picked from commit a7af950)

Author: rstoyanchev

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/RequestMappingInfoHandlerMapping.java

@@ -18,7 +18,6 @@
 
 import java.util.*;
 import java.util.Map.Entry;
-import java.util.Set;
 
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;