[Health Check] Refactor health_check methods to return a tuple (status, message) Closes #3906

[sanjib2006]

closes #3906

Description

• updated return type of health_check methods of plugins to return a tuple[bool, str] (status - true/false, message)
• updated tests related to this change

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality).

Checklist

• I have read and understood the rules about how to Contribute to this project
• The pull request is for the branch gsoc-2026/post-mid-connectors
• After you had submitted the PR, if DeepSource, Django Doctors or other third-party linters have triggered any alerts during the CI checks, I have solved those alerts.

[sanjib2006]

Hey @mlodic, could you please have a look at this?

I'm not sure why the DeepSource: Python check is suddenly flagging PluginConfigViewSet.plugin_config, since that method wasn't modified in this PR. DeepSource also mentions that the baseline analysis may not be accurate because the parent branch doesn't have its own PR, so this could be a pre-existing issue.

Would you prefer that I refactor the method to satisfy the check, or is it okay to merge with this failing check if it's unrelated to this PR? We may refactor later on if required through a new PR while merging it to the main/develop branch.

[mlodic]

deepsource can be ignored