[JENKINS-60866] Un-inline setup wizard root URL js (#7619)

* Un-inline setup wizard root URL

* Fix linting

core/src/main/resources/jenkins/install/SetupWizard/setInitialRootUrlFieldValue.js

+var rootUrlField = $("root-url");
+
+rootUrlField.focus();
+rootUrlField.onkeydown = function (event) {
+  if (event.keyCode == 13) {
+    event.preventDefault();
+  }
+};
+
+(function setInitialRootUrlFieldValue() {
+  var iframeUrl = window.location.href;
+  // will let the trailing slash in the rootUrl
+  var iframeRelativeUrl = "setupWizard/setupWizardConfigureInstance";
+  var rootUrl = iframeUrl.substr(
+    0,
+    iframeUrl.length - iframeRelativeUrl.length
+  );
+  // to keep only the root url
+  rootUrlField.value = rootUrl;
+  // to adjust the width of the input,
+  rootUrlField.size = Math.min(50, rootUrl.length);
+})();

core/src/main/resources/jenkins/install/SetupWizard/setupWizardConfigureInstance.jelly

@@ -22,7 +22,7 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 -->
 <?jelly escape-by-default='true'?>
-<j:jelly xmlns:j="jelly:core" xmlns:l="/lib/layout">
+<j:jelly xmlns:j="jelly:core" xmlns:l="/lib/layout" xmlns:st="jelly:stapler">
 
   <l:layout norefresh="true" type="full-screen" title="${it.displayName}">
     <l:main-panel>
@@ -45,27 +45,7 @@ THE SOFTWARE.
             </tr>
             </table>
           </div>
-         <script>
-            var rootUrlField = $('root-url');
-
-            rootUrlField.focus();
-            rootUrlField.onkeydown = function(event) {
-                if (event.keyCode == 13){
-                    event.preventDefault();
-                }
-            };
-
-            (function setInitialRootUrlFieldValue(){
-              var iframeUrl = window.location.href;
-              // will let the trailing slash in the rootUrl
-              var iframeRelativeUrl = 'setupWizard/setupWizardConfigureInstance';
-              var rootUrl = iframeUrl.substr(0, iframeUrl.length - iframeRelativeUrl.length);
-              // to keep only the root url
-              rootUrlField.value = rootUrl
-              // to adjust the width of the input,
-              rootUrlField.size = Math.min(50, rootUrl.length);
-            })();
-          </script>
+         <st:adjunct includes="jenkins.install.SetupWizard.setInitialRootUrlFieldValue"/>
         </form>
      </div>
     </l:main-panel>