Revert OPT_IN_MARKER_ON_OVERRIDE limitation #KT-48890 Fixed

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalOnOverrideWarning.kt

@@ -1,13 +0,0 @@
-// FIR_IDENTICAL
-// !OPT_IN: kotlin.RequiresOptIn
-// !LANGUAGE: -OptInOnOverrideForbidden
-
-@RequiresOptIn(level = RequiresOptIn.Level.WARNING)
-@Retention(AnnotationRetention.BINARY)
-annotation class E
-
-class My {
-    <!OPT_IN_MARKER_ON_OVERRIDE_WARNING!>@E<!>
-    override fun hashCode() = 0
-}
-

compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalOnOverrideWarning.txt

@@ -1,15 +0,0 @@
-package
-
-@kotlin.RequiresOptIn(level = Level.WARNING) @kotlin.annotation.Retention(value = AnnotationRetention.BINARY) public final annotation class E : kotlin.Annotation {
-    public constructor E()
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}
-
-public final class My {
-    public constructor My()
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    @E public open override /*1*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}

compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectTargetsForExperimentalAnnotation.kt

@@ -1,6 +1,5 @@
 // FIR_IDENTICAL
 // !OPT_IN: kotlin.RequiresOptIn
-// !LANGUAGE: +OptInOnOverrideForbidden
 // FILE: api.kt
 
 package api
@@ -57,7 +56,7 @@ var some: Int
 val another: Int = 42
 
 class My {
-    <!OPT_IN_MARKER_ON_OVERRIDE!>@E6<!>
+    @E6
     override fun hashCode() = 0
 }
 
@@ -73,7 +72,7 @@ interface Base {
 }
 
 class Derived : Base {
-    <!OPT_IN_MARKER_ON_OVERRIDE!>@E6<!>
+    @E6
     override val bar: Int = 42
 
     @set:E6 <!OPT_IN_MARKER_ON_WRONG_TARGET!>@setparam:E6<!>