[SPARK-51173][TESTS] Add configName Scalastyle rule

This PR aims to add `configName` Scalastyle rule to prevent invalid config names.

To prevent repetitive mistake pattern
- #45649
- #48149
- #49121

No.

Currently, this PR will fail at Scalastyle test because the `master` branch is broken. We can merge this after the following PR.
- #49897

No.

Closes #49900 from dongjoon-hyun/SPARK-51173.

Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
(cherry picked from commit 274dc5e)
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>

Author: dongjoon-hyun

scalastyle-config.xml

@@ -462,4 +462,9 @@ This file is divided into 3 sections:
       and URIs to and from String. If possible, please use SparkPath.
     ]]></customMessage>
   </check>
+
+  <check customId="configName" level="error" class="org.scalastyle.file.RegexChecker" enabled="true">
+    <parameters><parameter name="regex">buildConf\("spark.databricks.</parameter></parameters>
+    <customMessage>Use Apache Spark config namespace.</customMessage>
+  </check>
 </scalastyle>