Revert "Rework BootRun so that it does not subclass JavaExec"

This reverts commit 6eee9de3c1.

Closes gh-10872

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/com/example/BootRunApplication.java

@@ -18,7 +18,6 @@ package com.example;
 
 import java.io.File;
 import java.lang.management.ManagementFactory;
-import java.util.Arrays;
 
 /**
  * Very basic application used for testing {@code BootRun}.
@@ -32,12 +31,6 @@ public class BootRunApplication {
 	}
 
 	public static void main(String[] args) {
-		dumpClassPath();
-		dumpArgs(args);
-		dumpJvmArgs();
-	}
-
-	private static void dumpClassPath() {
 		int i = 1;
 		for (String entry : ManagementFactory.getRuntimeMXBean().getClassPath()
 				.split(File.pathSeparator)) {
@@ -45,12 +38,4 @@ public class BootRunApplication {
 		}
 	}
 
-	private static void dumpArgs(String[] args) {
-		System.out.println(Arrays.toString(args));
-	}
-
-	private static void dumpJvmArgs() {
-		System.out.println(ManagementFactory.getRuntimeMXBean().getInputArguments());
-	}
-
 }