[Native] Return kotlinCompilerRepo parameter back

This parameter is used to specify maven path in case of kotlin_version
rewriting that happens during Nightly test runs.

kotlin-native/samples/gradle.properties

@@ -8,6 +8,9 @@ org.gradle.workers.max=4
 # CHANGE_VERSION_WITH_RELEASE
 kotlin_version=1.4.30
 
+# Sets maven path for the kotlin version other than release
+#kotlinCompilerRepo=
+
 # Use custom Kotlin/Native home:
 kotlin.native.home=../../dist