Fix wrong import in Guava auto-config

Remove the need for `commons-collections`

See gh-2633

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cache/GuavaCacheConfiguration.java

@@ -18,7 +18,6 @@ package org.springframework.boot.autoconfigure.cache;
 
 import java.util.List;
 
-import org.apache.commons.collections.CollectionUtils;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -27,6 +26,7 @@ import org.springframework.cache.guava.GuavaCacheManager;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
 
 import com.google.common.cache.CacheBuilder;