K2: don't make T = Type! substitutions for constructors, including SAM

Without this commit we get some ABI changes and it looks bad.

Related to KT-65596

compiler/fir/analysis-tests/testData/resolve/samConstructors/genericSam.fir.txt

@@ -1,6 +1,6 @@
 FILE: main.kt
     public final fun main(): R|kotlin/Unit| {
-        R|/MyFunction|<R|kotlin/Int!|, R|kotlin/String!|>(<L> = MyFunction@fun <anonymous>(x: R|kotlin/Int!|): R|kotlin/String!| <inline=NoInline>  {
+        R|/MyFunction|<R|kotlin/Int|, R|kotlin/String|>(<L> = MyFunction@fun <anonymous>(x: R|kotlin/Int!|): R|kotlin/String!| <inline=NoInline>  {
             ^ R|<local>/x|.R|kotlin/Int.toInt|().R|kotlin/Int.toString|()
         }
         )