Use tcp sensor available flag to reflect connection errors

[fopina]

Breaking change

• before: when a connection fails, there is no state change - it remains with the value from the last successful connection
• now: when a connection fails, state is updated to unavailable

This might have impact on automations / triggers as unavailable state was not used before, not sure if that's considered breaking change.

Proposed change

Currently when a TCP sensor fails to connect (DNS failure, port is closed, host is not reachable or connection times out), state does not reflect it. It continues to show the last successful connection which is not accurate.

I propose to use sensor available flag by setting it to False whenever a connection exception occurs

Type of change

• [ ] Dependency upgrade
• [x] 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:

Checklist

• [x] The code change is tested and works locally.
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[fopina]

@MartinHjelmare thanks for the title fix. Anyone that could be pinged for this, as there is no codeowner pinged automatically by the bot?

[home-assistant[bot]]

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[github-actions[bot]]

There hasn't been any activity on this pull request recently. This pull request has been automatically marked as stale because of that and will be closed if no further activity occurs within 7 days. If you are the author of this PR, please leave a comment if you want to keep it open. Also, please rebase your PR onto the latest dev branch to ensure that it's up to date with the latest changes. Thank you for your contribution!

[fopina]

coming back to this, no need to close

[frenck]

Because there hasn't been any activity on this PR for quite some time now, I've decided to close it for being stale.

Feel free to re-open this PR when you are ready to pick up work on it again 👍

../Frenck