make some tests faster (#9413)

* remove duplicated slow test

* smaller `convex hull`

* smaller sleep

* faster `trtree`

* smaller sleep in `tfuturestream`

tests/async/tfuturestream.nim

@@ -19,7 +19,7 @@ var fs = newFutureStream[int]()
 proc alpha() {.async.} =
   for i in 0 .. 5:
     await fs.write(i)
-    await sleepAsync(1000)
+    await sleepAsync(200)
 
   echo("Done")
   fs.complete()