Use the concentrator time to calculate the server and wait time

[halimi]

Summary

References: https://github.com/TheThingsIndustries/lorawan-stack-support/issues/1370

Use the concentrator time instead of the packet timestamp to calculate the server and wait time when 'schedule downlink late` is enabled. The packet timestamp (microsecond timestamp) can overflow when the packet is scheduled in the future due to the duty cycle limit.

Changes

• Use the concentrator time to calculate the server and wait time

Testing

Steps

See the reproduction steps in https://github.com/TheThingsIndustries/lorawan-stack-support/issues/1370

Results

Regressions

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Notes for Reviewers

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Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• Testing: The steps/process to test this feature are clearly explained including testing for regressions.
• Infrastructure: If infrastructural changes (e.g., new RPC, configuration) are needed, a separate issue is created in the infrastructural repositories.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.