[FE] Make constructors of sealed classes protected instead of internal

compiler/testData/loadJava/compiledKotlin/annotations/classMembers/HiddenConstructorWithInlineClassParameters.txt

@@ -5,7 +5,7 @@ public final annotation class Ann : kotlin.Annotation {
 }
 
 public sealed class Sealed {
-    /*primary*/ @test.Ann internal constructor Sealed(/*0*/ @test.Ann z: test.Z)
+    /*primary*/ @test.Ann protected constructor Sealed(/*0*/ @test.Ann z: test.Z)
     public final val z: test.Z
         public final fun <get-z>(): test.Z
 

compiler/testData/loadJava/compiledKotlin/class/SealedClass.txt

@@ -9,7 +9,7 @@ public final class Inheritor3 : test.SealedClass {
 }
 
 public sealed class SealedClass {
-    /*primary*/ internal constructor SealedClass()
+    /*primary*/ protected constructor SealedClass()
 
     public final class Inheritor1 : test.SealedClass {
         /*primary*/ public constructor Inheritor1()