K2: repeat K1 representation for flexible type parameters

This commit changes the behavior of KT-59138 effectively declining it in 2.0.
However, we plan to implement KT-59138 behavior under a feature
flag in 2.0 (see KT-66447), and switch this feature on version 2.x.

Also, this commit implements the LC resolution about postponing
KT-57014 change. We don't have KT-57014 described behavior in 2.0 anymore.
However, we plan to implement a deprecation warning here, see KT-65578.

After this commit, 6 diagnostic tests become incorrectly broken:
- 5 tests from PurelyImplementedCollection group
- a test platformTypes/nullableTypeArgument.kt

This commit also breaks currently fixed-in-k2 KT-50134
(it is fixed again in the following commits),
as well as KT-58933 (it will remain not fixed till we enable KT-59138
behavior again).

#KT-65596 In Progress
#KT-57014 In Progress
#KT-58933 Submitted

analysis/analysis-api/testData/components/scopeProvider/memberScope/javaClass.pretty.txt

@@ -1,6 +1,6 @@
 open fun hello()
 
-open fun <T : kotlin.Any!> method(vararg classes: java.lang.Class<out (T & kotlin.Any..T?)>!)
+open fun <T : kotlin.Any!> method(vararg classes: java.lang.Class<out T!>!)
 
 @java.lang.Override
 open fun getActualRandomNumber(): kotlin.Int

analysis/analysis-api/testData/components/scopeProvider/memberScope/javaClass.txt

@@ -82,7 +82,7 @@ KtFunctionSymbol:
       receiverParameter: null
       returnType: KtFlexibleType:
         annotationsList: []
-        type: ft<java/lang/Class<out ft<T & Any, T?>>, java/lang/Class<out ft<T & Any, T?>>?>
+        type: ft<java/lang/Class<out T!>, java/lang/Class<out T!>?>
       symbolKind: LOCAL
       typeParameters: []
       getContainingFileSymbol: null

analysis/analysis-api/testData/components/scopeProvider/substitutionOverridesUnwrapping/Implement_java_util_Collection.pretty.txt

@@ -8,7 +8,7 @@ override operator fun iterator(): kotlin.collections.MutableIterator<test.SomeCl
 
 fun toArray(): kotlin.Array<kotlin.Any!>!
 
-fun <T : kotlin.Any!> toArray(p0: kotlin.Array<(T & kotlin.Any..T?)>!): kotlin.Array<(T & kotlin.Any..T?)>!
+fun <T : kotlin.Any!> toArray(p0: kotlin.Array<T!>!): kotlin.Array<T!>!
 
 override fun add(p0: test.SomeClass!): kotlin.Boolean