Impacted versions:
9.0, 10.0, 11.0 (Maybe 8.0)
I don't know if it is really an expected behaviour for odoo but I like to expose it

Steps to reproduce:

1. Open an ir.cron record and change it to:
 - interval: minutes
 - next execution date: now + 1 minute

2. Open the odoo server log

Note: I'm using workers=3 but I don't know if there is possible to reproduce it without workers.

Current behavior:

You will see for each cron execution the following output
```txt
...
2018-06-01 16:18:33,432 20686 INFO 333561-11-0-42aff9-all odoo.modules.registry: Invalidating all model caches after database signaling.
...
2018-06-01 16:17:21,527 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: loading 1 modules...
2018-06-01 16:17:21,535 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: 1 modules loaded in 0.01s, 0 queries
2018-06-01 16:17:21,594 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: loading 206 modules...
2018-06-01 16:17:21,718 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: 206 modules loaded in 0.12s, 0 queries
2018-06-01 16:17:21,989 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: Modules loaded.
```

Expected behavior:
 - Review if the method that run from the cron really requires a invalidate cache and delete all registries.
 - Disable "minutes" for cron interval because all cache are deleted then is not valid use them.

Video/Screenshot link (optional):

 - [![IMAGE ALT TEXT HERE](https://img.youtube.com/vi/Be4FIeQjgjk/0.jpg)](https://youtu.be/Be4FIeQjgjk)
if self.long_polling_pid is not None:
            
            self.worker_kill(self.long_polling_pid, signal.SIGKILL)
            self.long_polling_pid = None
        if graceful:
            _logger.info("Stopping gracefully")
            limit = time.time() + self.timeout
            for pid in self.workers.keys():
                self.worker_kill(pid, signal.SIGINT)
            while self.workers and time.time() < limit:
                try:
                    self.process_signals()
                except KeyboardInterrupt:
                    _logger.info("Forced shutdown.")
                    break
                self.process_zombie()
                time.sleep(0.1)
        else:
            _logger.info("Stopping forcefully")
        for pid in self.workers.keys():
            self.worker_kill(pid, signal.SIGTERM)
        if self.socket:
            self.socket.close()
    def run(self, preload, stop):