revert commons-io to 2.6 (#11392)

* * revert commons-io to 2.6

* * fix failing tests
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 717d6a0..9a4fbf3 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -9,3 +9,5 @@
       # pin ZooKeeper dependencies to 3.5.x
       - dependency-name: "org.apache.zookeeper"
         versions: "[3.6,)"
+      # Keep commons-io at 2.6 until https://issues.apache.org/jira/browse/IO-741 is resolved
+      - dependency-name: "commons-io:commons-io"
diff --git a/extensions-core/protobuf-extensions/pom.xml b/extensions-core/protobuf-extensions/pom.xml
index c3e1880..c523ec2 100644
--- a/extensions-core/protobuf-extensions/pom.xml
+++ b/extensions-core/protobuf-extensions/pom.xml
@@ -35,7 +35,7 @@
 
   <properties>
     <confluent.version>6.0.1</confluent.version>
-    <commons-io.version>2.9.0</commons-io.version>
+    <commons-io.version>2.6</commons-io.version>
   </properties>
 
   <repositories>
diff --git a/licenses.yaml b/licenses.yaml
index b521443..cf31a40 100644
--- a/licenses.yaml
+++ b/licenses.yaml
@@ -545,13 +545,13 @@
 license_category: binary
 module: java-core
 license_name: Apache License version 2.0
-version: 2.9.0
+version: 2.6
 libraries:
   - commons-io: commons-io
 notices:
   - commons-io: |
       Apache Commons IO
-      Copyright 2002-2021 The Apache Software Foundation
+      Copyright 2002-2017 The Apache Software Foundation
 
 ---
 
diff --git a/pom.xml b/pom.xml
index ffa549f..fd31c0f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -223,7 +223,7 @@
             <dependency>
                 <groupId>commons-io</groupId>
                 <artifactId>commons-io</artifactId>
-                <version>2.9.0</version>
+                <version>2.6</version>
             </dependency>
             <dependency>
                 <groupId>commons-logging</groupId>
diff --git a/server/src/test/java/org/apache/druid/segment/loading/LocalDataSegmentPusherTest.java b/server/src/test/java/org/apache/druid/segment/loading/LocalDataSegmentPusherTest.java
index 5ecca15..b6a0d85 100644
--- a/server/src/test/java/org/apache/druid/segment/loading/LocalDataSegmentPusherTest.java
+++ b/server/src/test/java/org/apache/druid/segment/loading/LocalDataSegmentPusherTest.java
@@ -153,7 +153,7 @@
   public void testPushCannotCreateDirectory() throws IOException
   {
     exception.expect(IOException.class);
-    exception.expectMessage("Cannot create directory");
+    exception.expectMessage("Unable to create directory");
     config.storageDirectory = new File(config.storageDirectory, "xxx");
     Assert.assertTrue(config.storageDirectory.mkdir());
     config.storageDirectory.setWritable(false);