Remove experimental coroutines opt-in from build scripts

It has no effect in Kotlin 1.3

Only enable coroutines if '-ReleaseCoroutines' is used

libraries/examples/scripting/jvm-simple-script/host/build.gradle.kts

@@ -1,4 +1,3 @@
-import org.jetbrains.kotlin.gradle.dsl.Coroutines
 
 plugins {
     kotlin("jvm")
@@ -17,7 +16,3 @@ sourceSets {
     "main" { projectDefault() }
     "test" { projectDefault() }
 }
-
-kotlin {
-    experimental.coroutines = Coroutines.ENABLE
-}