Do not schedule too far ahead

[halimi]

Summary

This is a backport of
https://github.com/TheThingsIndustries/lorawan-stack/pull/4841
https://github.com/TheThingsIndustries/lorawan-stack/pull/4843

Due to the recent change #7832 in the scheduler we see a memory increase in GS.
This fix tries to avoid to schedule an emission to far ahead in the future, holding a go routine to long time, causing a memory increase.
Also stops the timer in the Schedule late force case if the context is cancelled.

References: https://github.com/TheThingsIndustries/lorawan-stack-support/issues/1427

Changes

• Add a check on duty cycle limit to avoid scheduling emission too far ahead in the future
• Stop the timer if the context is cancelled

Testing

Steps

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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.