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/isInitializedAndDeinitialize/innerSubclass.kt

@@ -1,4 +1,3 @@
-// LANGUAGE_VERSION: 1.2
 // WITH_RUNTIME
 
 open class Foo {

compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/sideEffects.kt

@@ -1,5 +1,4 @@
 // IGNORE_BACKEND: JVM_IR
-// LANGUAGE_VERSION: 1.2
 // WITH_RUNTIME
 
 class Foo {

compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/simpleIsInitialized.kt

@@ -1,5 +1,4 @@
 // TARGET_BACKEND: JVM
-// LANGUAGE_VERSION: 1.2
 // WITH_RUNTIME
 
 // FILE: J.java

compiler/testData/codegen/box/properties/lateinit/isInitializedAndDeinitialize/topLevelProperty.kt

@@ -1,4 +1,3 @@
-// LANGUAGE_VERSION: 1.2
 // WITH_RUNTIME
 
 lateinit var bar: String