[JENKINS-71272] ensure proper confirmDelete jelly is used

solves the issue for the price of duplication of the confirmDelete file

src/main/resources/hudson/matrix/MatrixRun/confirmDelete.jelly

@@ -0,0 +1,53 @@
+<!--
+The MIT License
+
+Copyright (c) 2004-2009, Sun Microsystems, Inc., Kohsuke Kawaguchi, id:cactusman
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+-->
+
+<!--
+ Modification of https://github.com/jenkinsci/jenkins/blob/master/core/src/main/resources/hudson/model/Run/confirmDelete.jelly
+
+ We copy this template in order to use it.deleteMessage instead of it.whyKeepLog as displayed message.
+ This is required in order to have a warning which does not prevent the actual deletion.
+-->
+
+<!-- Confirm deletion of the build/run -->
+<?jelly escape-by-default='true'?>
+<j:jelly xmlns:j="jelly:core" xmlns:st="jelly:stapler" xmlns:d="jelly:define" xmlns:l="/lib/layout"
+         xmlns:t="/lib/hudson" xmlns:f="/lib/form" xmlns:i="jelly:fmt">
+  <l:layout title="${it.fullDisplayName}" norefresh="true">
+    <st:include page="sidepanel.jelly"/>
+    <l:main-panel>
+      <j:set var="msg" value="${it.deleteMessage}"/>
+      <j:if test="${msg!=null}">
+        <p class="warning">${%Warning}: ${msg}</p>
+      </j:if>
+
+      <j:if test="${it.whyKeepLog==null}">
+        <form method="post" action="doDelete">
+          ${%Are you sure about deleting the build?}
+          <f:submit value="${%Yes}"/>
+        </form>
+      </j:if>
+
+    </l:main-panel>
+  </l:layout>
+</j:jelly>