Migrate repo to use JVM toolchains Gradle feature.

^KT-46972 Fixed

libraries/stdlib/samples/build.gradle

@@ -11,7 +11,6 @@ sourceSets {
 
 compileTestKotlin {
     kotlinOptions {
-        jdkHome = JDK_18
         freeCompilerArgs = [
                 "-Xopt-in=kotlin.ExperimentalStdlibApi",
                 "-Xopt-in=kotlin.ExperimentalUnsignedTypes",
@@ -19,7 +18,3 @@ compileTestKotlin {
         ]
     }
 }
-
-test {
-    executable = "$JDK_18/bin/java"
-}