FIR: Do not add alias for variables with explicit type

compiler/testData/diagnostics/tests/Variance.fir.kt

@@ -11,10 +11,10 @@ fun foo(c: Consumer<Int>, p: Producer<Int>, u: Usual<Int>) {
     val c2: Consumer<Int> = c1
 
     val p1: Producer<Any> = p
-    val p2: Producer<Int> = p1
+    val p2: Producer<Int> = <!INITIALIZER_TYPE_MISMATCH!>p1<!>
 
     val u1: Usual<Any> = <!INITIALIZER_TYPE_MISMATCH!>u<!>
-    val u2: Usual<Int> = u1
+    val u2: Usual<Int> = <!INITIALIZER_TYPE_MISMATCH!>u1<!>
 }
 
 //Arrays copy example
@@ -37,4 +37,4 @@ fun f(ints: Array<Int>, any: Array<Any>, numbers: Array<Number>) {
     copy2(ints, <!ARGUMENT_TYPE_MISMATCH!>numbers<!>)
     copy3<Int>(ints, numbers)
     copy4(ints, numbers) //ok
-}
+}