Remove LANGUAGE_VERSION directive from blackBox codegen tests

compiler/testData/codegen/box/nullabilityAssertions/incWithNullabilityAssertionOnExtensionReceiverInPrivateOperator_lv11.kt

@@ -1,7 +1,7 @@
+// !LANGUAGE: -NullabilityAssertionOnExtensionReceiver
 // TARGET_BACKEND: JVM
 // FILE: test.kt
 // WITH_RUNTIME
-// LANGUAGE_VERSION: 1.1
 private operator fun A.inc() = A()
 
 fun box(): String {

compiler/testData/codegen/box/nullabilityAssertions/nullabilityAssertionOnExtensionReceiver_lv11.kt

@@ -1,7 +1,7 @@
+// !LANGUAGE: -NullabilityAssertionOnExtensionReceiver
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
 // FILE: test.kt
-// LANGUAGE_VERSION: 1.1
 import kotlin.test.*
 
 fun String.extension() {}

compiler/testData/codegen/box/nullabilityAssertions/nullabilityAssertionOnInlineFunExtensionReceiver_lv11.kt

@@ -1,7 +1,7 @@
+// !LANGUAGE: -NullabilityAssertionOnExtensionReceiver
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
 // FILE: test.kt
-// LANGUAGE_VERSION: 1.1
 import kotlin.test.*
 
 inline fun String.extension() {}