Debounce and group mqtt unsubscribes

[jbouwh]

Proposed change

When shutting down MQTT, and during a reload of the entry MQTT subscriptions will be unsubscribed at the broker.
This PR debounces the unsubscribe calls so then can be grouped gaining performance.

See also: #92172

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)
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• This PR fixes or closes issue: fixes #
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[home-assistant]

Hey there @emontnemery, 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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[jbouwh]

@corporategoth Anything that is not addressed yet, but should be?

[bdraco]

LGTM 👍

[emontnemery]

LGTM, thanks @jbouwh 👍