close #5342 add testcase (#17230)

* remove unnecessary when statement

* remove outdated codes

* close #5342 add testcase

* update the example

tests/destructor/t5342.nim

@@ -0,0 +1,23 @@
+discard """
+  matrix: "--gc:refc; --gc:arc"
+  output: '''
+1
+2
+here
+2
+1
+'''
+"""
+
+
+type
+  A = object
+    id: int
+  B = object
+    a: A
+proc `=destroy`(a: var A) = echo a.id
+var x = A(id: 1)
+var y = B(a: A(id: 2))
+`=destroy`(x)
+`=destroy`(y)
+echo "here"