fix: Handle messages republished by MQTT bridge following a disconnection event

[jarhodes314]

Proposed changes

The OSADL device running the built in bridge was occasionally disconnecting from cloud while sending messages and then failing to recover upon reconnection. The root cause was that unacknowledged messages were being republished by rumqttc upon reconnection, but the code was always waiting for a corresponding event from the other half of the bridge (as it implicitly assumed each message was only published once). Since there was no such corresponding event, this caused the bridge to block.

This PR ignores the duplicate publishes in the section of code that was blocking to fix this bug.

Note: The PR includes a workaround for the detected flaky test

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

• built-in bridge connection not sending or receiving messages from the cloud #2960

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s)
• I ran cargo fmt as mentioned in CODING_GUIDELINES
• I used cargo clippy as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[codecov]

Codecov Report

Attention: Patch coverage is 81.81818% with 2 lines in your changes missing coverage. Please review.

Project coverage is 78.1%. Comparing base (e637b25) to head (1cab1a7).
Report is 5 commits behind head on main.

Additional details and impacted files

Files	Coverage Δ
crates/extensions/tedge_mqtt_bridge/src/lib.rs	89.2% <81.8%> (-0.2%)	⬇️

... and 3 files with indirect coverage changes

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
486	0	2	486	100	1h19m55.609488s

[rina23q]

Only with minor comments

[jarhodes314]

I've now removed the commented out code and tidied up the import.

@reubenmiller suggested that I should also modify the JWT retrieving logic in the auth proxy so that it doesn't panic when we don't retrieve a JWT, although that isn't trivial and I think trying to get that change rushed in is more likely to do harm than good. I'm confident that the panicking JWT handler isn't the root cause (if the auth proxy panicking was causing the bridge to go down, I would expect it to crash the entire mapper, and the same error appeared multiple times, so the panic is limited to just the single request to the auth proxy).

[rina23q]

LGTM

There are more changes after my approval, therefore, I dismiss this approval

[rina23q]

Re-approved