fixes #22360; compare with the half of randMax (#22361)

* fixes #22360; compare with the half of randMax

* add a test

(cherry picked from commit f3a7622514)

lib/pure/random.nim

@@ -381,10 +381,7 @@ proc rand*[T: Ordinal](r: var Rand; t: typedesc[T]): T {.since: (1, 7, 1).} =
   when T is range or T is enum:
     result = rand(r, low(T)..high(T))
   elif T is bool:
-    whenJsNoBigInt64:
-      result = (r.next or 0) < 0
-    do:
-      result = cast[int64](r.next) < 0
+    result = r.next < randMax div 2
   else:
     whenJsNoBigInt64:
       result = cast[T](r.next shr (sizeof(uint)*8 - sizeof(T)*8))