AbstractScriptConfigurationTest: rewrite script template setup

Allow simpler setup of common scenarios
Do not require to define DependenciesResolver for every test
Drop redundant template files

idea/testData/script/definition/highlighting/additionalImports/script.kts

@@ -5,3 +5,5 @@ val g = listOf("a", "b", "c")
 val time = measureNanoTime {
     println("text")
 }
+
+// DEPENDENCIES: classpath:runtime-classes; imports:kotlin.system.*