Minor, move old Java nullability assertion tests under oldLanguageVersions/

Also drop the (now confusing) "_lv12" suffix from newer tests

compiler/testData/codegen/box/oldLanguageVersions/javaInterop/notNullAssertions/incWithNullabilityAssertionOnExtensionReceiverInPrivateOperator_lv11.kt

@@ -0,0 +1,17 @@
+// !LANGUAGE: -NullabilityAssertionOnExtensionReceiver
+// TARGET_BACKEND: JVM
+// FILE: test.kt
+// WITH_RUNTIME
+private operator fun A.inc() = A()
+
+fun box(): String {
+    var aNull = A.n()
+    aNull++
+    // NB no exception is thrown in language version 1.1
+    return "OK"
+}
+
+// FILE: A.java
+public class A {
+    public static A n() { return null; }
+}

compiler/testData/codegen/box/oldLanguageVersions/javaInterop/notNullAssertions/incWithNullabilityAssertionOnExtensionReceiver_lv11.kt

@@ -0,0 +1,23 @@
+// !LANGUAGE: -NullabilityAssertionOnExtensionReceiver
+// IGNORE_BACKEND_FIR: JVM_IR
+// TARGET_BACKEND: JVM
+// FILE: test.kt
+// WITH_RUNTIME
+
+import kotlin.test.*
+
+operator fun A.inc() = A()
+
+fun box(): String {
+    assertFailsWith<IllegalArgumentException> {
+        var aNull = A.n()
+        aNull++
+    }
+
+    return "OK"
+}
+
+// FILE: A.java
+public class A {
+    public static A n() { return null; }
+}

compiler/testData/codegen/box/oldLanguageVersions/javaInterop/notNullAssertions/nullabilityAssertionOnExtensionReceiver_lv11.kt

@@ -0,0 +1,18 @@
+// !LANGUAGE: -NullabilityAssertionOnExtensionReceiver
+// IGNORE_BACKEND_FIR: JVM_IR
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+// FILE: test.kt
+import kotlin.test.*
+
+fun String.extension() {}
+
+fun box(): String {
+    assertFailsWith<IllegalArgumentException> { J.s().extension() }
+    return "OK"
+}
+
+// FILE: J.java
+public class J {
+    public static String s() { return null; }
+}

compiler/testData/codegen/box/oldLanguageVersions/javaInterop/notNullAssertions/nullabilityAssertionOnInlineFunExtensionReceiver_lv11.kt

@@ -0,0 +1,17 @@
+// !LANGUAGE: -NullabilityAssertionOnExtensionReceiver
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+// FILE: test.kt
+import kotlin.test.*
+
+inline fun String.extension() {}
+
+fun box(): String {
+    J.s().extension() // NB no exception thrown
+    return "OK"
+}
+
+// FILE: J.java
+public class J {
+    public static String s() { return null; }
+}