Enable parallel flags in functional tests (#1292)

* Enabling parallel configuration caching

https://docs.gradle.org/current/userguide/configuration_cache.html#config_cache:usage:parallel

* Enable parallel execution

https://docs.gradle.org/current/userguide/performance.html#parallel_execution

Author: Goooler

src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/BasePluginTest.kt

@@ -381,7 +381,10 @@ abstract class BasePluginTest {
       "--warning-mode=fail",
       "--configuration-cache",
       "--build-cache",
+      "--parallel",
       "--stacktrace",
+      // https://docs.gradle.org/current/userguide/configuration_cache.html#config_cache:usage:parallel
+      "-Dorg.gradle.configuration-cache.parallel=true",
     )
 
     fun String.toProperties(): Properties = Properties().apply { load(byteInputStream()) }