Move server process creation to JDK 6 suite

It's allow to avoid problem with wrong inherited output
 (gradle instead of test process)

compiler/tests-different-jdk/build.gradle.kts

@@ -42,36 +42,12 @@ fun Project.codegenTest(target: Int, jvm: Int,
 codegenTest(target = 6, jvm = 6, jdk = "JDK_18") {
     dependsOn(testJvm6ServerRuntime)
 
-    val port = project.findProperty("kotlin.compiler.codegen.tests.port")?.toString() ?: "5100"
-    var jdkProcess: Process? = null
-
-    doFirst {
-        logger.info("Configuring JDK 6 server...")
-        val jdkPath = project.findProperty("JDK_16") ?: error("JDK_16 is not optional to run this test")
-        val executable = "$jdkPath/bin/java"
-        val main = "org.jetbrains.kotlin.test.clientserver.TestProcessServer"
-        val classpath = testJvm6ServerRuntime.asPath
-
-        logger.debug("Server classpath: $classpath")
-
-        val builder = ProcessBuilder(executable, "-cp", classpath, main, port)
-        builder.directory(rootDir)
-
-        builder.inheritIO()
-        builder.redirectErrorStream(true)
-
-        logger.info("Starting JDK 6 server $executable")
-        jdkProcess = builder.start()
-
-    }
     systemProperty("kotlin.test.default.jvm.target", "1.6")
     systemProperty("kotlin.test.java.compilation.target", "1.6")
-    systemProperty("kotlin.test.box.in.separate.process.port", port)
 
-    doLast {
-        logger.info("Stopping JDK 6 server...")
-        jdkProcess?.destroy()
-    }
+    val port = project.findProperty("kotlin.compiler.codegen.tests.port") ?: "5100"
+    systemProperty("kotlin.test.box.in.separate.process.port", port)
+    systemProperty("kotlin.test.box.in.separate.process.server.classpath", testJvm6ServerRuntime.asPath)
 }
 
 codegenTest(target = 6, jvm = 9) {