Fix checkstyle (opensearch-project#3283)

Fix checkstyle. Now it works as expected.

The problem is that chectyle works only with one config file. It does
not support multiple files except per-defined files like
`suppressions.xml`.
So the previous config effectively replaced `sun_checks.xml` and
validated only `System.out.println` lines in `tools`.
Since `println_checks.xml` replaced the main file we did not notice that
new version of checktyle removed `PrintlnModule` from the code base.

Changes:
- All code related to checking `tools` folder was moved in the main file
- Renamed the `sun_...xml` file to the `checktyle.xml` which is default
settings for checkstyle so we can track changes in it
- Set the latest version for `checktyle` so it can validate new JDK
features as well
 - Fixed problematic files which checkstyle highlighted

`System.out.println` I tested manually all I can say it works :-)

- [ ] New functionality includes testing
- [ ] New functionality has been documented
- [ ] Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and
signing off your commits, please check
[here](https://github.com/opensearch-project/OpenSearch/blob/main/CONTRIBUTING.md#developer-certificate-of-origin).

Signed-off-by: Andrey Pleskach <ples@aiven.io>
(cherry picked from commit cd45e78)

build.gradle

@@ -322,8 +322,8 @@ jacocoTestReport {
 }
 
 checkstyle {
-    configFile file("checkstyle/sun_checks.xml")
-    configFile file("checkstyle/println_checks.xml")
+    toolVersion "10.3.3"
+    configDirectory.set(rootProject.file("checkstyle/"))
 }
 
 opensearchplugin {

checkstyle/sun_checks.xml → checkstyle/checkstyle.xml

@@ -19,7 +19,7 @@
   To suppress certain violations please review suppression filters.
   Finally, it is worth reading the documentation.
 -->
-
+<!-- exSUN codestyle check with the additional check for System.out.ptintln -->
 <module name="Checker">
   <!--
       If you set the basedir property below, then all reported file
@@ -36,6 +36,13 @@
   <module name="BeforeExecutionExclusionFileFilter">
     <property name="fileNamePattern" value="module\-info\.java$"/>
   </module>
+  <!-- System.out.ptintln -->
+  <module name="BeforeExecutionExclusionFileFilter">
+    <property name="fileNamePattern" value="src/main/java/org/opensearch/security/tools/*"/>
+  </module>
+  <module name="BeforeExecutionExclusionFileFilter">
+    <property name="fileNamePattern" value="src/main/java/com/amazon/dlic/auth/http/kerberos/HTTPSpnegoAuthenticator.java"/>
+  </module>
 
   <!-- https://checkstyle.org/config_filters.html#SuppressionFilter -->
   <module name="SuppressionFilter">
@@ -188,6 +195,14 @@
       <property name="optional" value="true"/>
     </module>
 
+    <!-- System.out.println -->
+    <module name="RegexpSinglelineJava">
+      <property name="format" value="System.out.println"/>
+      <property name="ignoreCase" value="true"/>
+      <property name="message" value="Do not use System.out.println" />
+      <property name="severity" value="error"/>
+    </module>
+
   </module>
 
   <module name="RegexpSingleline">
@@ -215,5 +230,4 @@
     <property name="checkFormat" value="$1"/>
   </module>
 
-  <module name="PrintlnModule"/>
 </module>