Always use Celsius in Shelly integration, part 2

[bieniu]

Breaking change

Proposed change

We want integration internally to always use Celsius, also for sleeping devices like H&T. This is a continuation of #80842.

EDIT:
After the discussion with @thecode I changed the code, now the unit of measurement is also restored from registry, as is the value. When the device sends a new state, the unit is set based on entity_description.

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• Dependency upgrade
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• Breaking change (fix/feature causing existing functionality to break)
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Additional information

• This PR fixes or closes issue: fixes "Always use Celsius in Shelly integration" is a breaking change #81494
• This PR is related to issue:
• Link to documentation pull request:

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[home-assistant]

Hey there @balloob, @thecode, @chemelli74, mind taking a look at this pull request as it has been labeled with an integration (shelly) you are listed as a code owner for? Thanks!

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[akx]

Smol typo - and should there be a test for this?

[bieniu]

@akx Currently, we do not have tests for sensor platform.

[thecode]

Tested on Gen1 DW2 and Gen2 Shelly Plus H&T.
Many thanks @bieniu for debugging this issue.