[SPARK-19464][CORE][YARN][TEST-HADOOP2.6] Remove support for Hadoop 2.5 and earlier

## What changes were proposed in this pull request?

- Remove support for Hadoop 2.5 and earlier
- Remove reflection and code constructs only needed to support multiple versions at once
- Update docs to reflect newer versions
- Remove older versions' builds and profiles.

## How was this patch tested?

Existing tests

Author: Sean Owen <sowen@cloudera.com>

Closes #16810 from srowen/SPARK-19464.

1 files changed, 0 insertions, 22 deletions

diff --git a/resource-managers/yarn/pom.xml b/resource-managers/yarn/pom.xml
index f090d2427d..92a33de0ae 100644
--- a/resource-managers/yarn/pom.xml
+++ b/resource-managers/yarn/pom.xml
@@ -125,34 +125,12 @@
       <scope>test</scope>
     </dependency>
 
-     <!--
-    See SPARK-3710. hadoop-yarn-server-tests in Hadoop 2.2 fails to pull some needed
-    dependencies, so they need to be added manually for the tests to work.
-    -->
-
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-yarn-server-tests</artifactId>
       <classifier>tests</classifier>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.mockito</groupId>
-      <artifactId>mockito-core</artifactId>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
-      <groupId>org.mortbay.jetty</groupId>
-      <artifactId>jetty</artifactId>
-      <version>6.1.26</version>
-      <exclusions>
-       <exclusion>
-        <groupId>org.mortbay.jetty</groupId>
-         <artifactId>servlet-api</artifactId>
-       </exclusion>
-      </exclusions>
-      <scope>test</scope>
-     </dependency>
 
      <!--
        Jersey 1 dependencies only required for YARN integration testing. Creating a YARN cluster