save another 33s of CI for tests/gc/gcleak.nim

tests/gc/gcleak.nim

@@ -12,7 +12,14 @@ type
 proc makeObj(): TTestObj =
   result.x = "Hello"
 
-for i in 1 .. 100_000:
+const numIter =
+  # see tests/gc/gcleak2.nim
+  when defined(boehmgc):
+    1_000
+  elif defined(gcMarkAndSweep): 10_000
+  else: 100_000
+
+for i in 1 .. numIter:
   when defined(gcMarkAndSweep) or defined(boehmgc):
     GC_fullcollect()
   var obj = makeObj()