Update remoting to 2.31 in the Jenkins core. (#2628)

The change introduces one serious bugfix (JENKINS-39596) and a bunch of various diagnostics improvements.

Bugfixes:

* [JENKINS-39596](https://issues.jenkins-ci.org/browse/JENKINS-39596) -
Jenkins URL in `hudson.remoting.Engine` was always `null` since `3.0`.
It was causing connection failures of Jenkins JNLP agents when using Java Web Start.
([PR #131](jenkinsci/remoting#131))
* [JENKINS-39617](https://issues.jenkins-ci.org/browse/JENKINS-39617) -
`hudson.remoting.Engine` was failing to establish connection if one of the URLs parameter in parameters was malformed.
([PR #131](jenkinsci/remoting#131))

Improvements:

* [JENKINS-39150](https://issues.jenkins-ci.org/browse/JENKINS-39150) -
Add logic for dumping diagnostics across all the channels.
([PR #122](jenkinsci/remoting#122), [PR #125](jenkinsci/remoting#125))
* [JENKINS-39543](https://issues.jenkins-ci.org/browse/JENKINS-39543) -
Improve the caller/callee correlation diagnostics in thread dumps.
([PR #119](jenkinsci/remoting#119))
* [JENKINS-39290](https://issues.jenkins-ci.org/browse/JENKINS-39290) -
Add the `org.jenkinsci.remoting.nio.NioChannelHub.disabled` flag for disabling NIO (mostly for debugging purposes).
([PR #123](jenkinsci/remoting#123))
* [JENKINS-38692](https://issues.jenkins-ci.org/browse/JENKINS-38692) -
Add extra logging to help diagnosing `IOHub` Thread spikes.
([PR #116](jenkinsci/remoting#116))
* [JENKINS-39289](https://issues.jenkins-ci.org/browse/JENKINS-39289) -
 When a proxy fails, report what caused the channel to go down.
([PR #128](jenkinsci/remoting#128))

pom.xml

@@ -180,7 +180,7 @@ THE SOFTWARE.
       <dependency>
         <groupId>org.jenkins-ci.main</groupId>
         <artifactId>remoting</artifactId>
-        <version>3.0</version>
+        <version>3.1</version>
       </dependency>
 
       <dependency>