Suez water: simplify config flow

[jb101010-2]

Proposed change

Simplify config flow for suez water. Counter_id can now be automatically be fetched by the integration.
The value is provided only in the source code of suez website and therefore not easily accessible to user not familiar with devlopment.
Still possible to explicitly set the value for user with multiple value or value defined elsewhere.

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 #
• This PR is related to issue:
• Link to documentation pull request:
  • Suez water: simplify config flow home-assistant.io#35638

Checklist

• The code change is tested and works locally.
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• Tests have been added to verify that the new code works.

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• Documentation added/updated for www.home-assistant.io

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[home-assistant]

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

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