Fix previous deleted and rediscovered MQTT devices are not placed in suggested area

[jbouwh]

Proposed change

When an MQTT device is removed, its deleted entry reference is kept.
When an MQTT device is then readded, a suggested area in the configuration should be respected, instead of restoring the area of the deleted entry.

Note that this fix will only work if the entity has a device configuration and the device was removed from the device registry before it was rediscovered.

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)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes Newly discovered devices via MQTT are no more in the suggested_area #162557
• This PR is related to issue:
• Link to documentation pull request:
• Link to developer documentation pull request:
• Link to frontend pull request:

Checklist

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[home-assistant]

Hey there @emontnemery, @bdraco, mind taking a look at this pull request as it has been labeled with an integration (mqtt) you are listed as a code owner for? Thanks!

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