Remove LANGUAGE_VERSION from non-coroutine codegen tests

Most of these tests used this directive as a way to opt in to a new
language feature, and most of those features are already stable for a
long time, so no opt-in is needed. Some other tests used the directive
to opt out from a language feature, replace those by the `LANGUAGE`
directive. One test used the directive to test behavior that actually
depended on the API version; use `API_VERSION` directive there instead.

compiler/testData/codegen/box/jdk/streamBackwardCompatibility.kt

@@ -1,8 +1,9 @@
+// !LANGUAGE: -AdditionalBuiltInsMembers
 // SKIP_JDK6
 // TARGET_BACKEND: JVM
-// LANGUAGE_VERSION: 1.0
 // WITH_RUNTIME
 // FULL_JDK
+
 class A(val x: List<String>) : List<String> by x
 
 fun box(): String {