Revert "MapR [SPARK-701] CVE-2019-17571 security vulnerability for for log4j-1.2.17.jar (apache#664)" (apache#668)

This reverts commit 8948477.

Author: Egor Krivokon

core/pom.xml

@@ -123,12 +123,6 @@
     <dependency>
       <groupId>org.apache.zookeeper</groupId>
       <artifactId>zookeeper</artifactId>
-      <exclusions>
-        <exclusion>
-          <groupId>log4j</groupId>
-          <artifactId>log4j</artifactId>
-        </exclusion>
-      </exclusions>
     </dependency>
 
     <!-- Jetty dependencies promoted to compile here so they are shaded

external/kafka-0-9-assembly/pom.xml

@@ -90,12 +90,6 @@
       <groupId>org.apache.zookeeper</groupId>
       <artifactId>zookeeper</artifactId>
       <scope>provided</scope>
-      <exclusions>
-        <exclusion>
-          <groupId>log4j</groupId>
-          <artifactId>log4j</artifactId>
-        </exclusion>
-      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.apache.logging.log4j</groupId>

external/kinesis-asl-assembly/pom.xml

@@ -124,12 +124,6 @@
       <groupId>org.apache.zookeeper</groupId>
       <artifactId>zookeeper</artifactId>
       <scope>provided</scope>
-      <exclusions>
-        <exclusion>
-          <groupId>log4j</groupId>
-          <artifactId>log4j</artifactId>
-        </exclusion>
-      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.slf4j</groupId>