vine: submit more when hungry

[JinZhou5042]

Proposed Changes

Fix #3957

The problem is that the DaskVine manager will take a while to initialize tasks when the graph is wide enough, this pr lets the manager to consider worker connections right after submitting a small number of tasks.

Merge Checklist

The following items must be completed before PRs can be merged.
Check these off to verify you have completed all steps.

• make test Run local tests prior to pushing.
• make format Format source code to comply with lint policies. Note that some lint errors can only be resolved manually (e.g., Python)
• make lint Run lint on source code prior to pushing.
• Manual Update: Update the manual to reflect user-visible changes.
• Type Labels: Select a github label for the type: bugfix, enhancement, etc.
• Product Labels: Select a github label for the product: TaskVine, Makeflow, etc.
• PR RTM: Mark your PR as ready to merge.

[btovar]

@JinZhou5042 One issue with this solution is that vine_hungry() is potentially an expensive operation. #3990 makes it a little more efficient by considering only some of the waiting tasks, but it may still be slow if there are many workers connected. I got an idea on how to make this more efficient as the number of workers does not change much every time we call vine_wait, but I have not added it to #3990.

vine_hungry is supposed to return the number of tasks that would make the managernot hungry. So rather than calling vine_hungry every time, I suggest you call it once like min_to_sate = manager.hungry(), and decrease min_to_sate until it gets to less than 1.