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/delegation/hiddenSuperOverrideIn1.0.kt

@@ -1,5 +1,3 @@
-// LANGUAGE_VERSION: 1.0
-
 public interface Base {
     fun test() = "base fail"
 }

compiler/testData/codegen/box/delegation/simple1.0.kt

@@ -1,6 +1,6 @@
+// !LANGUAGE: -NoDelegationToJavaDefaultInterfaceMembers
 // SKIP_JDK6
 // TARGET_BACKEND: JVM
-// LANGUAGE_VERSION: 1.0
 // FILE: Base.java
 
 public interface Base {