Drop KotlinTarget.INNER_CLASS entry

In most of the cases it was used together with CLASS_ONLY and vice versa
They only case when CLASS_ONLY was used without INNER_CLASS
is possibleParentTargetMap.COMPANION_KEYWORD.

But after diagnostic NESTED_OBJECT_NOT_ALLOWED has been introduced,
there's no sense in the restriction of exactly the companion's parent

For clarification see test data changed

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/KeywordCompletion.kt

@@ -321,7 +321,7 @@ object KeywordCompletion {
 
                         is KtEnumEntry -> listOf(ENUM_ENTRY)
 
-                        is KtClassBody -> listOf(CLASS_ONLY, INTERFACE, OBJECT, ENUM_CLASS, ANNOTATION_CLASS, INNER_CLASS, MEMBER_FUNCTION, MEMBER_PROPERTY, FUNCTION, PROPERTY)
+                        is KtClassBody -> listOf(CLASS_ONLY, INTERFACE, OBJECT, ENUM_CLASS, ANNOTATION_CLASS, MEMBER_FUNCTION, MEMBER_PROPERTY, FUNCTION, PROPERTY)
 
                         is KtFile -> listOf(CLASS_ONLY, INTERFACE, OBJECT, ENUM_CLASS, ANNOTATION_CLASS, TOP_LEVEL_FUNCTION, TOP_LEVEL_PROPERTY, FUNCTION, PROPERTY)
 
@@ -339,7 +339,6 @@ object KeywordCompletion {
                                 ownerDeclaration.isInterface() -> KotlinTarget.INTERFACE
                                 ownerDeclaration.isEnum() -> KotlinTarget.ENUM_CLASS
                                 ownerDeclaration.isAnnotation() -> KotlinTarget.ANNOTATION_CLASS
-                                ownerDeclaration.isInner() -> KotlinTarget.INNER_CLASS
                                 else -> KotlinTarget.CLASS_ONLY
                             }
                         }