Fix withDebug benchOnly command (#8769)

Author: Pavel Marek

project/WithDebugCommand.scala

@@ -100,10 +100,18 @@ object WithDebugCommand {
           state.fail
         case Some(taskKey) =>
           val extracted = Project.extract(state)
-          val withJavaOpts = extracted.appendWithoutSession(
-            Seq(Compile / Keys.javaOptions ++= javaOpts),
-            state
-          )
+          // Append the java options also to the Benchmark configuration, in case we run `benchOnly`
+          // task.
+          val Benchmark = config("bench")
+          val withJavaOpts = extracted
+            .appendWithoutSession(
+              Seq(Compile / Keys.javaOptions ++= javaOpts),
+              state
+            )
+            .appendWithoutSession(
+              Seq(Benchmark / Keys.javaOptions ++= javaOpts),
+              state
+            )
           Project
             .extract(withJavaOpts)
             .runInputTask(taskKey, runArgs, withJavaOpts)