Scheduler will lost the registered executor when restart it in the `push` mode

**Describe the bug**
When i restart the schedule, the schedule lost all the information of registered executor

**To Reproduce**
Start a scheduler with below config:
```
scheduler_policy="PushStaged"
```
Start a executor with below config:
```
scheduler_port=50050
scheduler_host="localhost"
# PushStaged or PullStaged
task_scheduling_policy="PushStaged"
```

then kill the scheduler and restart the scheduler using the same config.

And the scheduler will lost all registered executor in the memory.

**Expected behavior**
We should recover this data in memory after the scheduler restart.

Solution:
heartbeat with the registered information for the executor

**Additional context**
Add any other context about the problem here.

Start by reproducing the restart scenario with scheduler_policy="PushStaged" and the provided executor configuration. Trace how registered executors are held and how heartbeat messages are handled; done means restarting the scheduler restores the executor registration in memory and the executor remains usable.

Written by the indexing model from the issue text.