ci: disable dotnet build servers + MSBuild node reuse to prevent Jenkins durable-task pipe-hold hang

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Jenkinsfile

@@ -131,7 +131,7 @@ pipeline {
     stage('Restore') {
       steps {
         dir(env.WORK_SUBDIR) {
-          bat 'chcp 65001 >NUL && dotnet restore %SLN_FILE%'
+          bat 'chcp 65001 >NUL && dotnet restore %SLN_FILE% --disable-build-servers'
         }
       }
     }
@@ -139,7 +139,7 @@ pipeline {
     stage('Build') {
       steps {
         dir(env.WORK_SUBDIR) {
-          bat 'chcp 65001 >NUL && dotnet build %SLN_FILE% -c Release --no-restore'
+          bat 'set MSBUILDDISABLENODEREUSE=1 && chcp 65001 >NUL && dotnet build %SLN_FILE% -c Release --no-restore --disable-build-servers'
         }
       }
     }