ORC-1673: Remove test packages o.a.o.tools.[count|merge|sizes]

### What changes were proposed in this pull request?

This PR aims to remove test packages, `o.a.o.tools.[count|merge|sizes]`, and move the test class to the parent directory.

### Why are the changes needed?

Those test packages have no corresponding source package. In other words, the main code is implemented in `o.a.o.tools` package.

### How was this patch tested?

Pass the CIs.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #1871 from dongjoon-hyun/ORC-1673.

Authored-by: Dongjoon Hyun <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>

java/tools/src/test/org/apache/orc/tools/sizes/TestColumnSizes.java → java/tools/src/test/org/apache/orc/tools/TestColumnSizes.java

@@ -16,7 +16,7 @@
  * limitations under the License.
  */
 
-package org.apache.orc.tools.sizes;
+package org.apache.orc.tools;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;

java/tools/src/test/org/apache/orc/tools/merge/TestMergeFiles.java → java/tools/src/test/org/apache/orc/tools/TestMergeFiles.java

@@ -16,7 +16,7 @@
  * limitations under the License.
  */
 
-package org.apache.orc.tools.merge;
+package org.apache.orc.tools;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;

java/tools/src/test/org/apache/orc/tools/count/TestRowCount.java → java/tools/src/test/org/apache/orc/tools/TestRowCount.java

@@ -16,7 +16,7 @@
  * limitations under the License.
  */
 
-package org.apache.orc.tools.count;
+package org.apache.orc.tools;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;