Update dependency org.jenkins-ci.main:jenkins-war to v2.440 (#2819)

* Update dependency org.jenkins-ci.main:jenkins-war to v2.440

* Removing declarative-pipeline-migration-assistant plugin because closed source dependency

* Revert "Removing declarative-pipeline-migration-assistant plugin because closed source dependency"

This reverts commit 60ac7d8.

* Bump declarative-pipeline-migration-assistant from 1.6.1 to 1.6.2

---------

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Adrien Lecharpentier <alecharpentier@cloudbees.com>

sample-plugin/pom.xml

@@ -14,7 +14,7 @@
   <properties>
     <changelist>999999-SNAPSHOT</changelist>
     <bom>weekly</bom>
-    <jenkins.version>2.439</jenkins.version>
+    <jenkins.version>2.440</jenkins.version>
     <spotless.check.skip>false</spotless.check.skip>
   </properties>
   <dependencyManagement>