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/properties/lateinit/topLevel/uninitializedRead.kt

@@ -1,4 +1,3 @@
-// LANGUAGE_VERSION: 1.2
 // WITH_RUNTIME
 
 import kotlin.UninitializedPropertyAccessException
@@ -17,4 +16,4 @@ fun box(): String {
     catch (e: Throwable) {
         return "Unexpected exception: ${e::class}"
     }
-}
+}