[FIR] Replace type variable types with error types in lambda completion

#KT-54568 Fixed
#KT-59882

compiler/testData/diagnostics/tests/regressions/kt10843.fir.kt

@@ -1,8 +1,7 @@
-// IGNORE_LEAKED_INTERNAL_TYPES: KT-54568
 // NI_EXPECTED_FILE
 // See EA-76890 / KT-10843: NPE during analysis
 fun lambda(x : Int?) = x?.<!FUNCTION_CALL_EXPECTED!>let<!> <!UNRESOLVED_REFERENCE!>l<!> {
-    y ->
+    <!CANNOT_INFER_PARAMETER_TYPE!>y<!> ->
     if (y <!UNRESOLVED_REFERENCE!>><!> 0) return@l x
     y
 }<!NOT_NULL_ASSERTION_ON_LAMBDA_EXPRESSION!>!!<!>

compiler/testData/diagnostics/tests/regressions/kt10843.kt

@@ -1,4 +1,3 @@
-// IGNORE_LEAKED_INTERNAL_TYPES: KT-54568
 // NI_EXPECTED_FILE
 // See EA-76890 / KT-10843: NPE during analysis
 fun lambda(x : Int?) = x?.<!FUNCTION_CALL_EXPECTED, NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER, NO_VALUE_FOR_PARAMETER!>let<!> <!DEBUG_INFO_MISSING_UNRESOLVED!>l<!> {