Prevent Bluetooth reconnects from blocking shutdown

[bdraco]

Proposed change

If a device tried to make a connection after all the Bluetooth scanners were already shutdown, it would wait in a loop for a scanner to become available before raising a BleakError. We now raise right away if the Bluetooth manager has been shutdown

This turned out to be more common than one would immediately expect as what happens is that the integration gets a callback that the Bluetooth device has been disconnected as a result of HA shutdown, but it does not know that HA is shutting down so it tries to re-establish the connection and shutdown waits for the task which will never be successful because all the scanners are already shutdown

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
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• Breaking change (fix/feature causing existing functionality to break)
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• This PR fixes or closes issue: fixes #
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[elupus]

Looks alright

[bdraco]

thanks