fix: allow concurrent tedge connect <cloud> --test processes

[rina23q]

Proposed changes

To support running multiple tedge connect test processes simultaneously, this change introduces a random suffix to the session name. This prevents naming conflicts when concurrent processes are executed.

Note: Although removing .with_session_name(CLIENT_ID) would technically resolve the issue, I chose to introduce .with_session_prefix() for a specific reason: keeping the prefix in the session name improves debuggability in MQTT logs, as the session name clearly identifies the source of each MQTT session.

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

#3907

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s. You can activate automatic signing by running just prepare-dev once)
• I ran just format as mentioned in CODING_GUIDELINES
• I used just check 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

❌ Patch coverage is 0% with 14 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/common/mqtt_channel/src/config.rs	0.00%	10 Missing ⚠️
crates/core/tedge/src/cli/connect/c8y.rs	0.00%	2 Missing ⚠️
crates/core/tedge/src/cli/connect/aws.rs	0.00%	1 Missing ⚠️
crates/core/tedge/src/cli/connect/azure.rs	0.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
755	0	4	755	100	2h29m8.605425999s

[didier-wenzek]

Approved